Re: Incremental View Maintenance, take 2
On Mon, 4 Sep 2023 16:48:02 +0800
jian he wrote:
> other ideas based on v29.
>
> src/include/utils/rel.h
> 680: #define RelationIsIVM(relation) ((relation)->rd_rel->relisivm)
> I guess it would be better to add some comments to address the usage.
> Since all peer macros all have some comments.
OK. I will add comments on this macro.
> pg_class change, I guess we need bump CATALOG_VERSION_NO?
CATALOG_VERSION_NO is frequently bumped up when new features are
committed, so including it in the patch causes frequent needs for
rebase during the review of the patch even if no meaningful change
is made. Therefore, I wonder we don't have to included it in the
patch at this time.
> small issue. makeIvmAggColumn and calc_delta need to add an empty
> return statement?
I'm sorry but I could not understand what you suggested, so could
you give me more explanation?
> style issue. in gram.y, "incremental" upper case?
> + CREATE OptNoLog incremental MATERIALIZED VIEW
> create_mv_target AS SelectStmt opt_with_data
This "incremental" is defined as INCREMENTAL or empty, as below.
incremental:INCREMENTAL { $$ = true; }
| /*EMPTY*/ { $$ = false; }
> I don't know how pgident works, do you need to add some keywords to
> src/tools/pgindent/typedefs.list to make indentation work?
I'm not sure typedefs.list should be updated in each patch, because
tools/pgindent/README said that the latest typedef file is downloaded
from the buildfarm when pgindent is run.
> in
> /* If this is not the last AFTER trigger call, immediately exit. */
> Assert (entry->before_trig_count >= entry->after_trig_count);
> if (entry->before_trig_count != entry->after_trig_count)
> return PointerGetDatum(NULL);
>
> before returning NULL, do you also need clean_up_IVM_hash_entry? (I
> don't know when this case will happen)
No, clean_up_IVM_hash_entry is not necessary in this case.
When multiple tables are updated in a statement, statement-level AFTER
triggers collects every information of the tables, and the last AFTER
trigger have to perform the actual maintenance of the view. To make sure
this, the number that BEFORE and AFTER trigger is fired is counted
respectively, and when they match it is regarded the last AFTER trigger
call performing the maintenance. Until this, collected information have
to keep, so we cannot call clean_up_IVM_hash_entry.
> in
> /* Replace the modified table with the new delta table and
> calculate the new view delta*/
> replace_rte_with_delta(rte, table, true, queryEnv);
> refresh_matview_datafill(dest_new, query, queryEnv, tupdesc_new, "");
>
> replace_rte_with_delta does not change the argument: table, argument:
> queryEnv. refresh_matview_datafill just uses the partial argument of
> the function calc_delta. So I guess, I am confused by the usage of
> replace_rte_with_delta. also I think it should return void, since you
> just modify the input argument. Here refresh_matview_datafill is just
> persisting new delta content to dest_new?
Yes, refresh_matview_datafill executes the query and the result rows to
"dest_new". And, replace_rte_with_delta updates the input argument "rte"
and returns the result to it, so it may be better that this returns void,
as you suggested.
Regards,
Yugo Nagata
--
Yugo NAGATA
Re: Incremental View Maintenance, take 2
On Fri, 1 Sep 2023 15:42:17 +0800
jian he wrote:
I apologize for this late reply.
> I added a new function append_update_set_caluse, and deleted
> functions: {append_set_clause_for_count, append_set_clause_for_sum,
> append_set_clause_for_avg, append_set_clause_for_minmax}
>
> I guess this way is more extensible/generic than yours.
Do you mean that consolidating such functions to a general function
make easier to support a new aggregate function in future? I'm not
convinced completely yet it because your suggestion seems that every
functions' logic are just put into a new function, but providing a
common interface might make a sense a bit.
By the way, when you attach files other than updated patches that
can be applied to master branch, using ".patch" or ".diff" as the
file extension help to avoid to confuse cfbot (for example, like
basedon_v29_matview_c_refactor_update_set_clause.patch.txt).
> src/backend/commands/matview.c
> 2268: /* For tuple deletion */
> maybe "/* For tuple deletion and update*/" is more accurate?
This "deletion" means deletion of tuple from the view rather
than DELETE statement, so I think this is ok.
> Since the apply delta query is quite complex, I feel like adding some
> "if debug then print out the final querybuf.data end if" would be a
> good idea.
Agreed, it would be helpful for debugging. I think it would be good
to add a debug macro that works if DEBUG_IVM is defined rather than
adding GUC like debug_print_..., how about it?
> we add hidden columns somewhere, also to avoid corner cases, so maybe
> somewhere we should assert total attribute number is sane.
The number of hidden columns to be added depends on the view definition
query, so I wonder the Assert condition would be a bit complex. Could
you explain what are you assume about like for example?
Regards,
Yugo Nagata
--
Yugo NAGATA
Re: Incremental View Maintenance, take 2
On Mon, 22 Jan 2024 13:51:08 +1100 Peter Smith wrote: > 2024-01 Commitfest. > > Hi, This patch has a CF status of "Needs Review" [1], but it seems > like there was some CFbot test failure last time it was run [2]. > Please have a look and post an updated version if necessary. Thank you for pointing out it. The CFbot failure is caused by a post [1] not by my patch-set, but regardless of it, I will heck if we need rebase and send the new version if necessary soon. [1] https://www.postgresql.org/message-id/CACJufxEoCCJE1vntJp1SWjen8vBUa3vZLgL%3DswPwar4zim976g%40mail.gmail.com Regards, Yugo Nagata > == > [1] https://commitfest.postgresql.org/46/4337/ > [2] https://cirrus-ci.com/task/6607979311529984 > > Kind Regards, > Peter Smith. -- Yugo NAGATA
Re: Incremental View Maintenance, take 2
2024-01 Commitfest. Hi, This patch has a CF status of "Needs Review" [1], but it seems like there was some CFbot test failure last time it was run [2]. Please have a look and post an updated version if necessary. == [1] https://commitfest.postgresql.org/46/4337/ [2] https://cirrus-ci.com/task/6607979311529984 Kind Regards, Peter Smith.
Re: Incremental View Maintenance, take 2
On Sat, Sep 2, 2023 at 7:46 PM Tatsuo Ishii wrote: > > > attached is my refactor. there is some whitespace errors in the > > patches, you need use > > git apply --reject --whitespace=fix > > basedon_v29_matview_c_refactor_update_set_clause.patch > > > > Also you patch cannot use git apply, i finally found out bulk apply > > I have no problem with applying Yugo's v29 patches using git apply, no > white space errors. > thanks. I downloaded the patches from the postgres website, then the problem was solved. other ideas based on v29. src/include/utils/rel.h 680: #define RelationIsIVM(relation) ((relation)->rd_rel->relisivm) I guess it would be better to add some comments to address the usage. Since all peer macros all have some comments. pg_class change, I guess we need bump CATALOG_VERSION_NO? small issue. makeIvmAggColumn and calc_delta need to add an empty return statement? style issue. in gram.y, "incremental" upper case? + CREATE OptNoLog incremental MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data I don't know how pgident works, do you need to add some keywords to src/tools/pgindent/typedefs.list to make indentation work? in /* If this is not the last AFTER trigger call, immediately exit. */ Assert (entry->before_trig_count >= entry->after_trig_count); if (entry->before_trig_count != entry->after_trig_count) return PointerGetDatum(NULL); before returning NULL, do you also need clean_up_IVM_hash_entry? (I don't know when this case will happen) in /* Replace the modified table with the new delta table and calculate the new view delta*/ replace_rte_with_delta(rte, table, true, queryEnv); refresh_matview_datafill(dest_new, query, queryEnv, tupdesc_new, ""); replace_rte_with_delta does not change the argument: table, argument: queryEnv. refresh_matview_datafill just uses the partial argument of the function calc_delta. So I guess, I am confused by the usage of replace_rte_with_delta. also I think it should return void, since you just modify the input argument. Here refresh_matview_datafill is just persisting new delta content to dest_new?
Re: Incremental View Maintenance, take 2
> attached is my refactor. there is some whitespace errors in the > patches, you need use > git apply --reject --whitespace=fix > basedon_v29_matview_c_refactor_update_set_clause.patch > > Also you patch cannot use git apply, i finally found out bulk apply I have no problem with applying Yugo's v29 patches using git apply, no white space errors. $ git apply ~/v29* (the patches are saved under my home directory). I suggest you to check your email application whether it correctly saved the patch files for you. FYI, here are results from sha256sum: ffac37cb455788c1105ffc01c6b606de75f53321c2f235f7efa19f3f52d12b9e v29-0001-Add-a-syntax-to-create-Incrementally-Maintainabl.patch f684485e7c9ac1b2990943a3c73fa49a9091a268917547d9e116baef5118cca7 v29-0002-Add-relisivm-column-to-pg_class-system-catalog.patch fcf5bc8ae562ed1c2ab397b499544ddab03ad2c3acb2263d0195a3ec799b131c v29-0003-Allow-to-prolong-life-span-of-transition-tables-.patch a7a13ef8e73c4717166db079d5607f78d21199379de341a0e8175beef5ea1c1a v29-0004-Add-Incremental-View-Maintenance-support-to-pg_d.patch a2aa51d035774867bfab1580ef14143998dc71c1b941bd1a3721dc019bc62649 v29-0005-Add-Incremental-View-Maintenance-support-to-psql.patch fe0225d761a08eb80082f1a2c039b9b8b20626169b03abaf649db9c74fe99194 v29-0006-Add-Incremental-View-Maintenance-support.patch 68b007befedcf92fc83ab8c3347ac047a50816f061c77b69281e12d52944db82 v29-0007-Add-DISTINCT-support-for-IVM.patch 2201241a22095f736a17383fc8b26d48a459ebf1c2f5cf120896cfc0ce5e03e4 v29-0008-Add-aggregates-support-in-IVM.patch 6390117c559bf1585349c5a09b77b784e086ccc22eb530cd364ce78371c66741 v29-0009-Add-support-for-min-max-aggregates-for-IVM.patch 7019a116c64127783bd9c682ddf1ee3792286d0e41c91a33010111e7be2c9459 v29-0010-Add-regression-tests-for-Incremental-View-Mainte.patch 189afdc7da866bd958e2d554ba12adf93d7e6d0acb581290a48d72fcf640e243 v29-0011-Add-documentations-about-Incremental-View-Mainte.patch Best reagards, -- Tatsuo Ishii SRA OSS LLC English: http://www.sraoss.co.jp/index_en/ Japanese:http://www.sraoss.co.jp
Re: Incremental View Maintenance, take 2
hi
based on v29.
based on https://stackoverflow.com/a/4014981/1560347:
I added a new function append_update_set_caluse, and deleted
functions: {append_set_clause_for_count, append_set_clause_for_sum,
append_set_clause_for_avg, append_set_clause_for_minmax}
I guess this way is more extensible/generic than yours.
replaced the following code with the generic function: append_update_set_caluse.
+ /* For views with aggregates, we need to build SET clause for
updating aggregate
+ * values. */
+ if (query->hasAggs && IsA(tle->expr, Aggref))
+ {
+ Aggref *aggref = (Aggref *) tle->expr;
+ const char *aggname = get_func_name(aggref->aggfnoid);
+
+ /*
+ * We can use function names here because it is already checked if these
+ * can be used in IMMV by its OID at the definition time.
+ */
+
+ /* count */
+ if (!strcmp(aggname, "count"))
+ append_set_clause_for_count(resname, aggs_set_old, aggs_set_new,
aggs_list_buf);
+
+ /* sum */
+ else if (!strcmp(aggname, "sum"))
+ append_set_clause_for_sum(resname, aggs_set_old, aggs_set_new, aggs_list_buf);
+
+ /* avg */
+ else if (!strcmp(aggname, "avg"))
+ append_set_clause_for_avg(resname, aggs_set_old, aggs_set_new, aggs_list_buf,
+ format_type_be(aggref->aggtype));
+
+ else
+ elog(ERROR, "unsupported aggregate function: %s", aggname);
+ }
--<<<
attached is my refactor. there is some whitespace errors in the
patches, you need use
git apply --reject --whitespace=fix
basedon_v29_matview_c_refactor_update_set_clause.patch
Also you patch cannot use git apply, i finally found out bulk apply
using gnu patch from
https://serverfault.com/questions/102324/apply-multiple-patch-files.
previously I just did it manually one by one.
I think if you use { for i in $PATCHES/v29*.patch; do patch -p1 < $i;
done } GNU patch, it will generate an .orig file for every modified
file?
-<
src/backend/commands/matview.c
2268: /* For tuple deletion */
maybe "/* For tuple deletion and update*/" is more accurate?
-<
currently at here: src/test/regress/sql/incremental_matview.sql
98: -- support SUM(), COUNT() and AVG() aggregate functions
99: BEGIN;
100: CREATE INCREMENTAL MATERIALIZED VIEW mv_ivm_agg AS SELECT i,
SUM(j), COUNT(i), AVG(j) FROM mv_base_a GROUP BY i;
101: SELECT * FROM mv_ivm_agg ORDER BY 1,2,3,4;
102: INSERT INTO mv_base_a VALUES(2,100);
src/backend/commands/matview.c
2858: if (SPI_exec(querybuf.data, 0) != SPI_OK_INSERT)
2859: elog(ERROR, "SPI_exec failed: %s", querybuf.data);
then I debug, print out querybuf.data:
WITH updt AS (UPDATE public.mv_ivm_agg AS mv SET __ivm_count__ =
mv.__ivm_count__ OPERATOR(pg_catalog.+) diff.__ivm_count__ , sum =
(CASE WHEN mv.__ivm_count_sum__ OPERATOR(pg_catalog.=) 0 AND
diff.__ivm_count_sum__ OPERATOR(pg_catalog.=) 0 THEN NULL WHEN mv.sum
IS NULL THEN diff.sum WHEN diff.sum IS NULL THEN mv.sum ELSE (mv.sum
OPERATOR(pg_catalog.+) diff.sum) END), __ivm_count_sum__ =
(mv.__ivm_count_sum__ OPERATOR(pg_catalog.+) diff.__ivm_count_sum__),
count = (mv.count OPERATOR(pg_catalog.+) diff.count), avg = (CASE WHEN
mv.__ivm_count_avg__ OPERATOR(pg_catalog.=) 0 AND
diff.__ivm_count_avg__ OPERATOR(pg_catalog.=) 0 THEN NULL WHEN
mv.__ivm_sum_avg__ IS NULL THEN diff.__ivm_sum_avg__ WHEN
diff.__ivm_sum_avg__ IS NULL THEN mv.__ivm_sum_avg__ ELSE
(mv.__ivm_sum_avg__ OPERATOR(pg_catalog.+)
diff.__ivm_sum_avg__)::numeric END) OPERATOR(pg_catalog./)
(mv.__ivm_count_avg__ OPERATOR(pg_catalog.+) diff.__ivm_count_avg__),
__ivm_sum_avg__ = (CASE WHEN mv.__ivm_count_avg__
OPERATOR(pg_catalog.=) 0 AND diff.__ivm_count_avg__
OPERATOR(pg_catalog.=) 0 THEN NULL WHEN mv.__ivm_sum_avg__ IS NULL
THEN diff.__ivm_sum_avg__ WHEN diff.__ivm_sum_avg__ IS NULL THEN
mv.__ivm_sum_avg__ ELSE (mv.__ivm_sum_avg__ OPERATOR(pg_catalog.+)
diff.__ivm_sum_avg__) END), __ivm_count_avg__ = (mv.__ivm_count_avg__
OPERATOR(pg_catalog.+) diff.__ivm_count_avg__) FROM new_delta AS diff
WHERE (mv.i OPERATOR(pg_catalog.=) diff.i OR (mv.i IS NULL AND diff.i
IS NULL)) RETURNING mv.i) INSERT INTO public.mv_ivm_agg (i, sum,
count, avg, __ivm_count_sum__, __ivm_count_avg__, __ivm_sum_avg__,
__ivm_count__) SELECT i, sum, count, avg, __ivm_count_sum__,
__ivm_count_avg__, __ivm_sum_avg__, __ivm_count__ FROM new_delta AS
diff WHERE NOT EXISTS (SELECT 1 FROM updt AS mv WHERE (mv.i
OPERATOR(pg_catalog.=) diff.i OR (mv.i IS NULL AND diff.i IS NULL)));
At this final SPI_exec, we have a update statement with related
columns { __ivm_count_sum__, sum, __ivm_count__, count, avg,
__ivm_sum_avg__, __ivm_count_avg__}. At this time, my mind stops
working, querybuf.data is way too big, but I still feel like there is
some logic associated with these columns, maybe we can use it as an
assertion to prove that this query (querybuf.len = 1834) is indeed
correct.
Since the apply delta query is quite complex, I feel like adding some
"if debug then print out the final querybuf.data end if" would be a
good idea.
we add hidden columns somewhere, also to avoid corner cases,
Re: Incremental View Maintenance, take 2
On Sun, 2 Jul 2023 10:38:20 +0800 jian he wrote: > ok. Now I really found a small bug. > > this works as intended: > BEGIN; > CREATE INCREMENTAL MATERIALIZED VIEW test_ivm AS SELECT i, MIN(j) as > min_j FROM mv_base_a group by 1; > INSERT INTO mv_base_a select 1,-2 where false; > rollback; > > however the following one: > BEGIN; > CREATE INCREMENTAL MATERIALIZED VIEW test_ivm1 AS SELECT MIN(j) as > min_j FROM mv_base_a; > INSERT INTO mv_base_a select 1, -2 where false; > rollback; > > will evaluate > tuplestore_tuple_count(new_tuplestores) to 1, it will walk through > IVM_immediate_maintenance function to apply_delta. > but should it be zero? This is not a bug because an aggregate without GROUP BY always results one row whose value is NULL. The contents of test_imv1 would be always same as " SELECT MIN(j) as min_j FROM mv_base_a;", isn't it? Regards, Yugo Nagata -- Yugo NAGATA
Re: Incremental View Maintenance, take 2
On Sun, 2 Jul 2023 08:25:12 +0800
jian he wrote:
> This is probably not trivial.
> In function apply_new_delta_with_count.
>
> appendStringInfo(,
> "WITH updt AS (" /* update a tuple if this exists in the view */
> "UPDATE %s AS mv SET %s = mv.%s OPERATOR(pg_catalog.+) diff.%s "
> "%s " /* SET clauses for aggregates */
> "FROM %s AS diff "
> "WHERE %s " /* tuple matching condition */
> "RETURNING %s" /* returning keys of updated tuples */
> ") INSERT INTO %s (%s)" /* insert a new tuple if this doesn't existw */
> "SELECT %s FROM %s AS diff "
> "WHERE NOT EXISTS (SELECT 1 FROM updt AS mv WHERE %s);",
>
> -
> ") INSERT INTO %s (%s)" /* insert a new tuple if this doesn't existw */
> "SELECT %s FROM %s AS diff "
>
> the INSERT INTO line, should have one white space in the end?
> also "existw" should be "exists"
Yes, we should need a space although it works. I'll fix as well as the typo.
Thank you.
Regards,
Yugo Nagata
--
Yugo NAGATA
Re: Incremental View Maintenance, take 2
On Fri, 30 Jun 2023 08:00:00 +0800 jian he wrote: > Hi there. > in v28-0005-Add-Incremental-View-Maintenance-support-to-psql.patch > I don't know how to set psql to get the output > "Incremental view maintenance: yes" This information will appear when you use "d+" command for an incrementally maintained materialized view. Regards, Yugo Nagata -- Yugo NAGATA
Re: Incremental View Maintenance, take 2
On Thu, 29 Jun 2023 18:51:06 +0800
jian he wrote:
> I cannot build the doc.
> git clean -fdx
> git am ~/Desktop/tmp/*.patch
>
> Applying: Add a syntax to create Incrementally Maintainable Materialized Views
> Applying: Add relisivm column to pg_class system catalog
> Applying: Allow to prolong life span of transition tables until transaction
> end
> Applying: Add Incremental View Maintenance support to pg_dump
> Applying: Add Incremental View Maintenance support to psql
> Applying: Add Incremental View Maintenance support
> Applying: Add DISTINCT support for IVM
> Applying: Add aggregates support in IVM
> Applying: Add support for min/max aggregates for IVM
> Applying: Add regression tests for Incremental View Maintenance
> Applying: Add documentations about Incremental View Maintenance
> .git/rebase-apply/patch:79: trailing whitespace.
> clause.
> warning: 1 line adds whitespace errors.
>
> Because of this, the {ninja docs} command failed. ERROR message:
>
> [6/6] Generating doc/src/sgml/html with a custom command
> FAILED: doc/src/sgml/html
> /usr/bin/python3
> ../../Desktop/pg_sources/main/postgres/doc/src/sgml/xmltools_dep_wrapper
> --targetname doc/src/sgml/html --depfile doc/src/sgml/html.d --tool
> /usr/bin/xsltproc -- -o doc/src/sgml/ --nonet --stringparam pg.version
> 16beta2 --path doc/src/sgml --path
> ../../Desktop/pg_sources/main/postgres/doc/src/sgml
> ../../Desktop/pg_sources/main/postgres/doc/src/sgml/stylesheet.xsl
> doc/src/sgml/postgres-full.xml
> ERROR: id attribute missing on element under /book[@id =
> 'postgres']/part[@id = 'server-programming']/chapter[@id =
> 'rules']/sect1[@id = 'rules-ivm']
> error: file doc/src/sgml/postgres-full.xml
> xsltRunStylesheet : run failed
> ninja: build stopped: subcommand failed.
Thank your for pointing out this.
I'll add ids for all sections to suppress the errors.
Regards,
Yugo Nagata
--
Yugo NAGATA
Re: Incremental View Maintenance, take 2
On Thu, 29 Jun 2023 18:20:32 +0800 jian he wrote: > On Thu, Jun 29, 2023 at 12:40 AM jian he wrote: > > > > On Wed, Jun 28, 2023 at 4:06 PM Yugo NAGATA wrote: > > > > > > On Wed, 28 Jun 2023 00:01:02 +0800 > > > jian he wrote: > > > > > > > On Thu, Jun 1, 2023 at 2:47 AM Yugo NAGATA wrote: > > > > > > > > > > On Thu, 1 Jun 2023 23:59:09 +0900 > > > > > Yugo NAGATA wrote: > > > > > > > > > > > Hello hackers, > > > > > > > > > > > > Here's a rebased version of the patch-set adding Incremental View > > > > > > Maintenance support for PostgreSQL. That was discussed in [1]. > > > > > > > > > > > [1] > > > > > > https://www.postgresql.org/message-id/flat/20181227215726.4d166b4874f8983a641123f5%40sraoss.co.jp > > > > > > > > > > --- > > > > > * Overview > > > > > > > > > > Incremental View Maintenance (IVM) is a way to make materialized views > > > > > up-to-date by computing only incremental changes and applying them on > > > > > views. IVM is more efficient than REFRESH MATERIALIZED VIEW when > > > > > only small parts of the view are changed. > > > > > > > > > > ** Feature > > > > > > > > > > The attached patchset provides a feature that allows materialized > > > > > views > > > > > to be updated automatically and incrementally just after a underlying > > > > > table is modified. > > > > > > > > > > You can create an incementally maintainable materialized view (IMMV) > > > > > by using CREATE INCREMENTAL MATERIALIZED VIEW command. > > > > > > > > > > The followings are supported in view definition queries: > > > > > - SELECT ... FROM ... WHERE ..., joins (inner joins, self-joins) > > > > > - some built-in aggregate functions (count, sum, avg, min, max) > > > > > - GROUP BY clause > > > > > - DISTINCT clause > > > > > > > > > > Views can contain multiple tuples with the same content (duplicate > > > > > tuples). > > > > > > > > > > ** Restriction > > > > > > > > > > The following are not supported in a view definition: > > > > > - Outer joins > > > > > - Aggregates otehr than above, window functions, HAVING > > > > > - Sub-queries, CTEs > > > > > - Set operations (UNION, INTERSECT, EXCEPT) > > > > > - DISTINCT ON, ORDER BY, LIMIT, OFFSET > > > > > > > > > > Also, a view definition query cannot contain other views, > > > > > materialized views, > > > > > foreign tables, partitioned tables, partitions, VALUES, non-immutable > > > > > functions, > > > > > system columns, or expressions that contains aggregates. > > > > > > > > > > --- > > > > > * Design > > > > > > > > > > An IMMV is maintained using statement-level AFTER triggers. > > > > > When an IMMV is created, triggers are automatically created on all > > > > > base > > > > > tables contained in the view definition query. > > > > > > > > > > When a table is modified, changes that occurred in the table are > > > > > extracted > > > > > as transition tables in the AFTER triggers. Then, changes that will > > > > > occur in > > > > > the view are calculated by a rewritten view dequery in which the > > > > > modified table > > > > > is replaced with the transition table. > > > > > > > > > > For example, if the view is defined as "SELECT * FROM R, S", and > > > > > tuples inserted > > > > > into R are stored in a transiton table dR, the tuples that will be > > > > > inserted into > > > > > the view are calculated as the result of "SELECT * FROM dR, S". > > > > > > > > > > ** Multiple Tables Modification > > > > > > > > > > Multiple tables can be modified in a statement when using triggers, > > > > > foreign key > > > > > constraint, or modifying CTEs. When multiple tables are modified, we > > > > > need > > > > > the state of tables before the modification. > > > > > > > > > > For example, when some tuples, dR and dS, are inserted into R and S > > > > > respectively, > > > > > the tuples that will be inserted into the view are calculated by the > > > > > following > > > > > two queries: > > > > > > > > > > "SELECT * FROM dR, S_pre" > > > > > "SELECT * FROM R, dS" > > > > > > > > > > where S_pre is the table before the modification, R is the current > > > > > state of > > > > > table, that is, after the modification. This pre-update states of > > > > > table > > > > > is calculated by filtering inserted tuples and appending deleted > > > > > tuples. > > > > > The subquery that represents pre-update state is generated in > > > > > get_prestate_rte(). > > > > > Specifically, the insterted tuples are filtered by calling > > > > > IVM_visible_in_prestate() > > > > > in WHERE clause. This function checks the visibility of tuples by > > > > > using > > > > > the snapshot taken before table modification. The deleted tuples are > > > > > contained > > > > > in the old transition table, and this table is appended using UNION > > > > > ALL. > > > > > > > > > > Transition tables
Re: Incremental View Maintenance, take 2
On Thu, 29 Jun 2023 00:40:45 +0800 jian he wrote: > On Wed, Jun 28, 2023 at 4:06 PM Yugo NAGATA wrote: > > > > On Wed, 28 Jun 2023 00:01:02 +0800 > > jian he wrote: > > > > > On Thu, Jun 1, 2023 at 2:47 AM Yugo NAGATA wrote: > > > > > > > > On Thu, 1 Jun 2023 23:59:09 +0900 > > > > Yugo NAGATA wrote: > > > > > > > > > Hello hackers, > > > > > > > > > > Here's a rebased version of the patch-set adding Incremental View > > > > > Maintenance support for PostgreSQL. That was discussed in [1]. > > > > > > > > > [1] > > > > > https://www.postgresql.org/message-id/flat/20181227215726.4d166b4874f8983a641123f5%40sraoss.co.jp > > > > > > > > --- > > > > * Overview > > > > > > > > Incremental View Maintenance (IVM) is a way to make materialized views > > > > up-to-date by computing only incremental changes and applying them on > > > > views. IVM is more efficient than REFRESH MATERIALIZED VIEW when > > > > only small parts of the view are changed. > > > > > > > > ** Feature > > > > > > > > The attached patchset provides a feature that allows materialized views > > > > to be updated automatically and incrementally just after a underlying > > > > table is modified. > > > > > > > > You can create an incementally maintainable materialized view (IMMV) > > > > by using CREATE INCREMENTAL MATERIALIZED VIEW command. > > > > > > > > The followings are supported in view definition queries: > > > > - SELECT ... FROM ... WHERE ..., joins (inner joins, self-joins) > > > > - some built-in aggregate functions (count, sum, avg, min, max) > > > > - GROUP BY clause > > > > - DISTINCT clause > > > > > > > > Views can contain multiple tuples with the same content (duplicate > > > > tuples). > > > > > > > > ** Restriction > > > > > > > > The following are not supported in a view definition: > > > > - Outer joins > > > > - Aggregates otehr than above, window functions, HAVING > > > > - Sub-queries, CTEs > > > > - Set operations (UNION, INTERSECT, EXCEPT) > > > > - DISTINCT ON, ORDER BY, LIMIT, OFFSET > > > > > > > > Also, a view definition query cannot contain other views, materialized > > > > views, > > > > foreign tables, partitioned tables, partitions, VALUES, non-immutable > > > > functions, > > > > system columns, or expressions that contains aggregates. > > > > > > > > --- > > > > * Design > > > > > > > > An IMMV is maintained using statement-level AFTER triggers. > > > > When an IMMV is created, triggers are automatically created on all base > > > > tables contained in the view definition query. > > > > > > > > When a table is modified, changes that occurred in the table are > > > > extracted > > > > as transition tables in the AFTER triggers. Then, changes that will > > > > occur in > > > > the view are calculated by a rewritten view dequery in which the > > > > modified table > > > > is replaced with the transition table. > > > > > > > > For example, if the view is defined as "SELECT * FROM R, S", and tuples > > > > inserted > > > > into R are stored in a transiton table dR, the tuples that will be > > > > inserted into > > > > the view are calculated as the result of "SELECT * FROM dR, S". > > > > > > > > ** Multiple Tables Modification > > > > > > > > Multiple tables can be modified in a statement when using triggers, > > > > foreign key > > > > constraint, or modifying CTEs. When multiple tables are modified, we > > > > need > > > > the state of tables before the modification. > > > > > > > > For example, when some tuples, dR and dS, are inserted into R and S > > > > respectively, > > > > the tuples that will be inserted into the view are calculated by the > > > > following > > > > two queries: > > > > > > > > "SELECT * FROM dR, S_pre" > > > > "SELECT * FROM R, dS" > > > > > > > > where S_pre is the table before the modification, R is the current > > > > state of > > > > table, that is, after the modification. This pre-update states of table > > > > is calculated by filtering inserted tuples and appending deleted tuples. > > > > The subquery that represents pre-update state is generated in > > > > get_prestate_rte(). > > > > Specifically, the insterted tuples are filtered by calling > > > > IVM_visible_in_prestate() > > > > in WHERE clause. This function checks the visibility of tuples by using > > > > the snapshot taken before table modification. The deleted tuples are > > > > contained > > > > in the old transition table, and this table is appended using UNION ALL. > > > > > > > > Transition tables for each modification are collected in each AFTER > > > > trigger > > > > function call. Then, the view maintenance is performed in the last call > > > > of > > > > the trigger. > > > > > > > > In the original PostgreSQL, tuplestores of transition tables are freed > > > > at the > > > > end of each nested query. However, their lifespan
Re: Incremental View Maintenance, take 2
ok. Now I really found a small bug. this works as intended: BEGIN; CREATE INCREMENTAL MATERIALIZED VIEW test_ivm AS SELECT i, MIN(j) as min_j FROM mv_base_a group by 1; INSERT INTO mv_base_a select 1,-2 where false; rollback; however the following one: BEGIN; CREATE INCREMENTAL MATERIALIZED VIEW test_ivm1 AS SELECT MIN(j) as min_j FROM mv_base_a; INSERT INTO mv_base_a select 1, -2 where false; rollback; will evaluate tuplestore_tuple_count(new_tuplestores) to 1, it will walk through IVM_immediate_maintenance function to apply_delta. but should it be zero?
Re: Incremental View Maintenance, take 2
This is probably not trivial.
In function apply_new_delta_with_count.
appendStringInfo(,
"WITH updt AS (" /* update a tuple if this exists in the view */
"UPDATE %s AS mv SET %s = mv.%s OPERATOR(pg_catalog.+) diff.%s "
"%s " /* SET clauses for aggregates */
"FROM %s AS diff "
"WHERE %s " /* tuple matching condition */
"RETURNING %s" /* returning keys of updated tuples */
") INSERT INTO %s (%s)" /* insert a new tuple if this doesn't existw */
"SELECT %s FROM %s AS diff "
"WHERE NOT EXISTS (SELECT 1 FROM updt AS mv WHERE %s);",
-
") INSERT INTO %s (%s)" /* insert a new tuple if this doesn't existw */
"SELECT %s FROM %s AS diff "
the INSERT INTO line, should have one white space in the end?
also "existw" should be "exists"
Re: Incremental View Maintenance, take 2
Hi there. in v28-0005-Add-Incremental-View-Maintenance-support-to-psql.patch I don't know how to set psql to get the output "Incremental view maintenance: yes"
Re: Incremental View Maintenance, take 2
On Thu, Jun 29, 2023 at 6:51 PM jian he wrote:
>
> I cannot build the doc.
> git clean -fdx
> git am ~/Desktop/tmp/*.patch
>
> Applying: Add a syntax to create Incrementally Maintainable Materialized Views
> Applying: Add relisivm column to pg_class system catalog
> Applying: Allow to prolong life span of transition tables until transaction
> end
> Applying: Add Incremental View Maintenance support to pg_dump
> Applying: Add Incremental View Maintenance support to psql
> Applying: Add Incremental View Maintenance support
> Applying: Add DISTINCT support for IVM
> Applying: Add aggregates support in IVM
> Applying: Add support for min/max aggregates for IVM
> Applying: Add regression tests for Incremental View Maintenance
> Applying: Add documentations about Incremental View Maintenance
> .git/rebase-apply/patch:79: trailing whitespace.
> clause.
> warning: 1 line adds whitespace errors.
>
> Because of this, the {ninja docs} command failed. ERROR message:
>
> [6/6] Generating doc/src/sgml/html with a custom command
> FAILED: doc/src/sgml/html
> /usr/bin/python3
> ../../Desktop/pg_sources/main/postgres/doc/src/sgml/xmltools_dep_wrapper
> --targetname doc/src/sgml/html --depfile doc/src/sgml/html.d --tool
> /usr/bin/xsltproc -- -o doc/src/sgml/ --nonet --stringparam pg.version
> 16beta2 --path doc/src/sgml --path
> ../../Desktop/pg_sources/main/postgres/doc/src/sgml
> ../../Desktop/pg_sources/main/postgres/doc/src/sgml/stylesheet.xsl
> doc/src/sgml/postgres-full.xml
> ERROR: id attribute missing on element under /book[@id =
> 'postgres']/part[@id = 'server-programming']/chapter[@id =
> 'rules']/sect1[@id = 'rules-ivm']
> error: file doc/src/sgml/postgres-full.xml
> xsltRunStylesheet : run failed
> ninja: build stopped: subcommand failed.
so far what I tried:
git am --ignore-whitespace --whitespace=nowarn ~/Desktop/tmp/*.patch
git am --whitespace=fix ~/Desktop/tmp/*.patch
git am --whitespace=error ~/Desktop/tmp/*.patch
I still cannot generate html docs.
Re: Incremental View Maintenance, take 2
I cannot build the doc.
git clean -fdx
git am ~/Desktop/tmp/*.patch
Applying: Add a syntax to create Incrementally Maintainable Materialized Views
Applying: Add relisivm column to pg_class system catalog
Applying: Allow to prolong life span of transition tables until transaction end
Applying: Add Incremental View Maintenance support to pg_dump
Applying: Add Incremental View Maintenance support to psql
Applying: Add Incremental View Maintenance support
Applying: Add DISTINCT support for IVM
Applying: Add aggregates support in IVM
Applying: Add support for min/max aggregates for IVM
Applying: Add regression tests for Incremental View Maintenance
Applying: Add documentations about Incremental View Maintenance
.git/rebase-apply/patch:79: trailing whitespace.
clause.
warning: 1 line adds whitespace errors.
Because of this, the {ninja docs} command failed. ERROR message:
[6/6] Generating doc/src/sgml/html with a custom command
FAILED: doc/src/sgml/html
/usr/bin/python3
../../Desktop/pg_sources/main/postgres/doc/src/sgml/xmltools_dep_wrapper
--targetname doc/src/sgml/html --depfile doc/src/sgml/html.d --tool
/usr/bin/xsltproc -- -o doc/src/sgml/ --nonet --stringparam pg.version
16beta2 --path doc/src/sgml --path
../../Desktop/pg_sources/main/postgres/doc/src/sgml
../../Desktop/pg_sources/main/postgres/doc/src/sgml/stylesheet.xsl
doc/src/sgml/postgres-full.xml
ERROR: id attribute missing on element under /book[@id =
'postgres']/part[@id = 'server-programming']/chapter[@id =
'rules']/sect1[@id = 'rules-ivm']
error: file doc/src/sgml/postgres-full.xml
xsltRunStylesheet : run failed
ninja: build stopped: subcommand failed.
Re: Incremental View Maintenance, take 2
On Thu, Jun 29, 2023 at 12:40 AM jian he wrote: > > On Wed, Jun 28, 2023 at 4:06 PM Yugo NAGATA wrote: > > > > On Wed, 28 Jun 2023 00:01:02 +0800 > > jian he wrote: > > > > > On Thu, Jun 1, 2023 at 2:47 AM Yugo NAGATA wrote: > > > > > > > > On Thu, 1 Jun 2023 23:59:09 +0900 > > > > Yugo NAGATA wrote: > > > > > > > > > Hello hackers, > > > > > > > > > > Here's a rebased version of the patch-set adding Incremental View > > > > > Maintenance support for PostgreSQL. That was discussed in [1]. > > > > > > > > > [1] > > > > > https://www.postgresql.org/message-id/flat/20181227215726.4d166b4874f8983a641123f5%40sraoss.co.jp > > > > > > > > --- > > > > * Overview > > > > > > > > Incremental View Maintenance (IVM) is a way to make materialized views > > > > up-to-date by computing only incremental changes and applying them on > > > > views. IVM is more efficient than REFRESH MATERIALIZED VIEW when > > > > only small parts of the view are changed. > > > > > > > > ** Feature > > > > > > > > The attached patchset provides a feature that allows materialized views > > > > to be updated automatically and incrementally just after a underlying > > > > table is modified. > > > > > > > > You can create an incementally maintainable materialized view (IMMV) > > > > by using CREATE INCREMENTAL MATERIALIZED VIEW command. > > > > > > > > The followings are supported in view definition queries: > > > > - SELECT ... FROM ... WHERE ..., joins (inner joins, self-joins) > > > > - some built-in aggregate functions (count, sum, avg, min, max) > > > > - GROUP BY clause > > > > - DISTINCT clause > > > > > > > > Views can contain multiple tuples with the same content (duplicate > > > > tuples). > > > > > > > > ** Restriction > > > > > > > > The following are not supported in a view definition: > > > > - Outer joins > > > > - Aggregates otehr than above, window functions, HAVING > > > > - Sub-queries, CTEs > > > > - Set operations (UNION, INTERSECT, EXCEPT) > > > > - DISTINCT ON, ORDER BY, LIMIT, OFFSET > > > > > > > > Also, a view definition query cannot contain other views, materialized > > > > views, > > > > foreign tables, partitioned tables, partitions, VALUES, non-immutable > > > > functions, > > > > system columns, or expressions that contains aggregates. > > > > > > > > --- > > > > * Design > > > > > > > > An IMMV is maintained using statement-level AFTER triggers. > > > > When an IMMV is created, triggers are automatically created on all base > > > > tables contained in the view definition query. > > > > > > > > When a table is modified, changes that occurred in the table are > > > > extracted > > > > as transition tables in the AFTER triggers. Then, changes that will > > > > occur in > > > > the view are calculated by a rewritten view dequery in which the > > > > modified table > > > > is replaced with the transition table. > > > > > > > > For example, if the view is defined as "SELECT * FROM R, S", and tuples > > > > inserted > > > > into R are stored in a transiton table dR, the tuples that will be > > > > inserted into > > > > the view are calculated as the result of "SELECT * FROM dR, S". > > > > > > > > ** Multiple Tables Modification > > > > > > > > Multiple tables can be modified in a statement when using triggers, > > > > foreign key > > > > constraint, or modifying CTEs. When multiple tables are modified, we > > > > need > > > > the state of tables before the modification. > > > > > > > > For example, when some tuples, dR and dS, are inserted into R and S > > > > respectively, > > > > the tuples that will be inserted into the view are calculated by the > > > > following > > > > two queries: > > > > > > > > "SELECT * FROM dR, S_pre" > > > > "SELECT * FROM R, dS" > > > > > > > > where S_pre is the table before the modification, R is the current > > > > state of > > > > table, that is, after the modification. This pre-update states of table > > > > is calculated by filtering inserted tuples and appending deleted tuples. > > > > The subquery that represents pre-update state is generated in > > > > get_prestate_rte(). > > > > Specifically, the insterted tuples are filtered by calling > > > > IVM_visible_in_prestate() > > > > in WHERE clause. This function checks the visibility of tuples by using > > > > the snapshot taken before table modification. The deleted tuples are > > > > contained > > > > in the old transition table, and this table is appended using UNION ALL. > > > > > > > > Transition tables for each modification are collected in each AFTER > > > > trigger > > > > function call. Then, the view maintenance is performed in the last call > > > > of > > > > the trigger. > > > > > > > > In the original PostgreSQL, tuplestores of transition tables are freed > > > > at the > > > > end of each nested query. However, their lifespan
Re: Incremental View Maintenance, take 2
On Wed, Jun 28, 2023 at 4:06 PM Yugo NAGATA wrote: > > On Wed, 28 Jun 2023 00:01:02 +0800 > jian he wrote: > > > On Thu, Jun 1, 2023 at 2:47 AM Yugo NAGATA wrote: > > > > > > On Thu, 1 Jun 2023 23:59:09 +0900 > > > Yugo NAGATA wrote: > > > > > > > Hello hackers, > > > > > > > > Here's a rebased version of the patch-set adding Incremental View > > > > Maintenance support for PostgreSQL. That was discussed in [1]. > > > > > > > [1] > > > > https://www.postgresql.org/message-id/flat/20181227215726.4d166b4874f8983a641123f5%40sraoss.co.jp > > > > > > --- > > > * Overview > > > > > > Incremental View Maintenance (IVM) is a way to make materialized views > > > up-to-date by computing only incremental changes and applying them on > > > views. IVM is more efficient than REFRESH MATERIALIZED VIEW when > > > only small parts of the view are changed. > > > > > > ** Feature > > > > > > The attached patchset provides a feature that allows materialized views > > > to be updated automatically and incrementally just after a underlying > > > table is modified. > > > > > > You can create an incementally maintainable materialized view (IMMV) > > > by using CREATE INCREMENTAL MATERIALIZED VIEW command. > > > > > > The followings are supported in view definition queries: > > > - SELECT ... FROM ... WHERE ..., joins (inner joins, self-joins) > > > - some built-in aggregate functions (count, sum, avg, min, max) > > > - GROUP BY clause > > > - DISTINCT clause > > > > > > Views can contain multiple tuples with the same content (duplicate > > > tuples). > > > > > > ** Restriction > > > > > > The following are not supported in a view definition: > > > - Outer joins > > > - Aggregates otehr than above, window functions, HAVING > > > - Sub-queries, CTEs > > > - Set operations (UNION, INTERSECT, EXCEPT) > > > - DISTINCT ON, ORDER BY, LIMIT, OFFSET > > > > > > Also, a view definition query cannot contain other views, materialized > > > views, > > > foreign tables, partitioned tables, partitions, VALUES, non-immutable > > > functions, > > > system columns, or expressions that contains aggregates. > > > > > > --- > > > * Design > > > > > > An IMMV is maintained using statement-level AFTER triggers. > > > When an IMMV is created, triggers are automatically created on all base > > > tables contained in the view definition query. > > > > > > When a table is modified, changes that occurred in the table are extracted > > > as transition tables in the AFTER triggers. Then, changes that will occur > > > in > > > the view are calculated by a rewritten view dequery in which the modified > > > table > > > is replaced with the transition table. > > > > > > For example, if the view is defined as "SELECT * FROM R, S", and tuples > > > inserted > > > into R are stored in a transiton table dR, the tuples that will be > > > inserted into > > > the view are calculated as the result of "SELECT * FROM dR, S". > > > > > > ** Multiple Tables Modification > > > > > > Multiple tables can be modified in a statement when using triggers, > > > foreign key > > > constraint, or modifying CTEs. When multiple tables are modified, we need > > > the state of tables before the modification. > > > > > > For example, when some tuples, dR and dS, are inserted into R and S > > > respectively, > > > the tuples that will be inserted into the view are calculated by the > > > following > > > two queries: > > > > > > "SELECT * FROM dR, S_pre" > > > "SELECT * FROM R, dS" > > > > > > where S_pre is the table before the modification, R is the current state > > > of > > > table, that is, after the modification. This pre-update states of table > > > is calculated by filtering inserted tuples and appending deleted tuples. > > > The subquery that represents pre-update state is generated in > > > get_prestate_rte(). > > > Specifically, the insterted tuples are filtered by calling > > > IVM_visible_in_prestate() > > > in WHERE clause. This function checks the visibility of tuples by using > > > the snapshot taken before table modification. The deleted tuples are > > > contained > > > in the old transition table, and this table is appended using UNION ALL. > > > > > > Transition tables for each modification are collected in each AFTER > > > trigger > > > function call. Then, the view maintenance is performed in the last call of > > > the trigger. > > > > > > In the original PostgreSQL, tuplestores of transition tables are freed at > > > the > > > end of each nested query. However, their lifespan needs to be prolonged to > > > the end of the out-most query in order to maintain the view in the last > > > AFTER > > > trigger. For this purpose, SetTransitionTablePreserved is added in > > > trigger.c. > > > > > > ** Duplicate Tulpes > > > > > > When calculating changes that will occur in the view (= delta
Re: Incremental View Maintenance, take 2
On Wed, 28 Jun 2023 00:01:02 +0800 jian he wrote: > On Thu, Jun 1, 2023 at 2:47 AM Yugo NAGATA wrote: > > > > On Thu, 1 Jun 2023 23:59:09 +0900 > > Yugo NAGATA wrote: > > > > > Hello hackers, > > > > > > Here's a rebased version of the patch-set adding Incremental View > > > Maintenance support for PostgreSQL. That was discussed in [1]. > > > > > [1] > > > https://www.postgresql.org/message-id/flat/20181227215726.4d166b4874f8983a641123f5%40sraoss.co.jp > > > > --- > > * Overview > > > > Incremental View Maintenance (IVM) is a way to make materialized views > > up-to-date by computing only incremental changes and applying them on > > views. IVM is more efficient than REFRESH MATERIALIZED VIEW when > > only small parts of the view are changed. > > > > ** Feature > > > > The attached patchset provides a feature that allows materialized views > > to be updated automatically and incrementally just after a underlying > > table is modified. > > > > You can create an incementally maintainable materialized view (IMMV) > > by using CREATE INCREMENTAL MATERIALIZED VIEW command. > > > > The followings are supported in view definition queries: > > - SELECT ... FROM ... WHERE ..., joins (inner joins, self-joins) > > - some built-in aggregate functions (count, sum, avg, min, max) > > - GROUP BY clause > > - DISTINCT clause > > > > Views can contain multiple tuples with the same content (duplicate tuples). > > > > ** Restriction > > > > The following are not supported in a view definition: > > - Outer joins > > - Aggregates otehr than above, window functions, HAVING > > - Sub-queries, CTEs > > - Set operations (UNION, INTERSECT, EXCEPT) > > - DISTINCT ON, ORDER BY, LIMIT, OFFSET > > > > Also, a view definition query cannot contain other views, materialized > > views, > > foreign tables, partitioned tables, partitions, VALUES, non-immutable > > functions, > > system columns, or expressions that contains aggregates. > > > > --- > > * Design > > > > An IMMV is maintained using statement-level AFTER triggers. > > When an IMMV is created, triggers are automatically created on all base > > tables contained in the view definition query. > > > > When a table is modified, changes that occurred in the table are extracted > > as transition tables in the AFTER triggers. Then, changes that will occur in > > the view are calculated by a rewritten view dequery in which the modified > > table > > is replaced with the transition table. > > > > For example, if the view is defined as "SELECT * FROM R, S", and tuples > > inserted > > into R are stored in a transiton table dR, the tuples that will be inserted > > into > > the view are calculated as the result of "SELECT * FROM dR, S". > > > > ** Multiple Tables Modification > > > > Multiple tables can be modified in a statement when using triggers, foreign > > key > > constraint, or modifying CTEs. When multiple tables are modified, we need > > the state of tables before the modification. > > > > For example, when some tuples, dR and dS, are inserted into R and S > > respectively, > > the tuples that will be inserted into the view are calculated by the > > following > > two queries: > > > > "SELECT * FROM dR, S_pre" > > "SELECT * FROM R, dS" > > > > where S_pre is the table before the modification, R is the current state of > > table, that is, after the modification. This pre-update states of table > > is calculated by filtering inserted tuples and appending deleted tuples. > > The subquery that represents pre-update state is generated in > > get_prestate_rte(). > > Specifically, the insterted tuples are filtered by calling > > IVM_visible_in_prestate() > > in WHERE clause. This function checks the visibility of tuples by using > > the snapshot taken before table modification. The deleted tuples are > > contained > > in the old transition table, and this table is appended using UNION ALL. > > > > Transition tables for each modification are collected in each AFTER trigger > > function call. Then, the view maintenance is performed in the last call of > > the trigger. > > > > In the original PostgreSQL, tuplestores of transition tables are freed at > > the > > end of each nested query. However, their lifespan needs to be prolonged to > > the end of the out-most query in order to maintain the view in the last > > AFTER > > trigger. For this purpose, SetTransitionTablePreserved is added in > > trigger.c. > > > > ** Duplicate Tulpes > > > > When calculating changes that will occur in the view (= delta tables), > > multiplicity of tuples are calculated by using count(*). > > > > When deleting tuples from the view, tuples to be deleted are identified by > > joining the delta table with the view, and tuples are deleted as many as > > specified multiplicity by numbered using row_number() function. > > This is
Re: Incremental View Maintenance, take 2
On Thu, Jun 1, 2023 at 2:47 AM Yugo NAGATA wrote: > > On Thu, 1 Jun 2023 23:59:09 +0900 > Yugo NAGATA wrote: > > > Hello hackers, > > > > Here's a rebased version of the patch-set adding Incremental View > > Maintenance support for PostgreSQL. That was discussed in [1]. > > > [1] > > https://www.postgresql.org/message-id/flat/20181227215726.4d166b4874f8983a641123f5%40sraoss.co.jp > > --- > * Overview > > Incremental View Maintenance (IVM) is a way to make materialized views > up-to-date by computing only incremental changes and applying them on > views. IVM is more efficient than REFRESH MATERIALIZED VIEW when > only small parts of the view are changed. > > ** Feature > > The attached patchset provides a feature that allows materialized views > to be updated automatically and incrementally just after a underlying > table is modified. > > You can create an incementally maintainable materialized view (IMMV) > by using CREATE INCREMENTAL MATERIALIZED VIEW command. > > The followings are supported in view definition queries: > - SELECT ... FROM ... WHERE ..., joins (inner joins, self-joins) > - some built-in aggregate functions (count, sum, avg, min, max) > - GROUP BY clause > - DISTINCT clause > > Views can contain multiple tuples with the same content (duplicate tuples). > > ** Restriction > > The following are not supported in a view definition: > - Outer joins > - Aggregates otehr than above, window functions, HAVING > - Sub-queries, CTEs > - Set operations (UNION, INTERSECT, EXCEPT) > - DISTINCT ON, ORDER BY, LIMIT, OFFSET > > Also, a view definition query cannot contain other views, materialized views, > foreign tables, partitioned tables, partitions, VALUES, non-immutable > functions, > system columns, or expressions that contains aggregates. > > --- > * Design > > An IMMV is maintained using statement-level AFTER triggers. > When an IMMV is created, triggers are automatically created on all base > tables contained in the view definition query. > > When a table is modified, changes that occurred in the table are extracted > as transition tables in the AFTER triggers. Then, changes that will occur in > the view are calculated by a rewritten view dequery in which the modified > table > is replaced with the transition table. > > For example, if the view is defined as "SELECT * FROM R, S", and tuples > inserted > into R are stored in a transiton table dR, the tuples that will be inserted > into > the view are calculated as the result of "SELECT * FROM dR, S". > > ** Multiple Tables Modification > > Multiple tables can be modified in a statement when using triggers, foreign > key > constraint, or modifying CTEs. When multiple tables are modified, we need > the state of tables before the modification. > > For example, when some tuples, dR and dS, are inserted into R and S > respectively, > the tuples that will be inserted into the view are calculated by the following > two queries: > > "SELECT * FROM dR, S_pre" > "SELECT * FROM R, dS" > > where S_pre is the table before the modification, R is the current state of > table, that is, after the modification. This pre-update states of table > is calculated by filtering inserted tuples and appending deleted tuples. > The subquery that represents pre-update state is generated in > get_prestate_rte(). > Specifically, the insterted tuples are filtered by calling > IVM_visible_in_prestate() > in WHERE clause. This function checks the visibility of tuples by using > the snapshot taken before table modification. The deleted tuples are contained > in the old transition table, and this table is appended using UNION ALL. > > Transition tables for each modification are collected in each AFTER trigger > function call. Then, the view maintenance is performed in the last call of > the trigger. > > In the original PostgreSQL, tuplestores of transition tables are freed at the > end of each nested query. However, their lifespan needs to be prolonged to > the end of the out-most query in order to maintain the view in the last AFTER > trigger. For this purpose, SetTransitionTablePreserved is added in trigger.c. > > ** Duplicate Tulpes > > When calculating changes that will occur in the view (= delta tables), > multiplicity of tuples are calculated by using count(*). > > When deleting tuples from the view, tuples to be deleted are identified by > joining the delta table with the view, and tuples are deleted as many as > specified multiplicity by numbered using row_number() function. > This is implemented in apply_old_delta(). > > When inserting tuples into the view, each tuple is duplicated to the > specified multiplicity using generate_series() function. This is implemented > in apply_new_delta(). > > ** DISTINCT clause > > When DISTINCT is used, the view has a hidden column __ivm_count__ that > stores
Re: Incremental View Maintenance, take 2
On Thu, 1 Jun 2023 23:59:09 +0900 Yugo NAGATA wrote: > Hello hackers, > > Here's a rebased version of the patch-set adding Incremental View > Maintenance support for PostgreSQL. That was discussed in [1]. > [1] > https://www.postgresql.org/message-id/flat/20181227215726.4d166b4874f8983a641123f5%40sraoss.co.jp --- * Overview Incremental View Maintenance (IVM) is a way to make materialized views up-to-date by computing only incremental changes and applying them on views. IVM is more efficient than REFRESH MATERIALIZED VIEW when only small parts of the view are changed. ** Feature The attached patchset provides a feature that allows materialized views to be updated automatically and incrementally just after a underlying table is modified. You can create an incementally maintainable materialized view (IMMV) by using CREATE INCREMENTAL MATERIALIZED VIEW command. The followings are supported in view definition queries: - SELECT ... FROM ... WHERE ..., joins (inner joins, self-joins) - some built-in aggregate functions (count, sum, avg, min, max) - GROUP BY clause - DISTINCT clause Views can contain multiple tuples with the same content (duplicate tuples). ** Restriction The following are not supported in a view definition: - Outer joins - Aggregates otehr than above, window functions, HAVING - Sub-queries, CTEs - Set operations (UNION, INTERSECT, EXCEPT) - DISTINCT ON, ORDER BY, LIMIT, OFFSET Also, a view definition query cannot contain other views, materialized views, foreign tables, partitioned tables, partitions, VALUES, non-immutable functions, system columns, or expressions that contains aggregates. --- * Design An IMMV is maintained using statement-level AFTER triggers. When an IMMV is created, triggers are automatically created on all base tables contained in the view definition query. When a table is modified, changes that occurred in the table are extracted as transition tables in the AFTER triggers. Then, changes that will occur in the view are calculated by a rewritten view dequery in which the modified table is replaced with the transition table. For example, if the view is defined as "SELECT * FROM R, S", and tuples inserted into R are stored in a transiton table dR, the tuples that will be inserted into the view are calculated as the result of "SELECT * FROM dR, S". ** Multiple Tables Modification Multiple tables can be modified in a statement when using triggers, foreign key constraint, or modifying CTEs. When multiple tables are modified, we need the state of tables before the modification. For example, when some tuples, dR and dS, are inserted into R and S respectively, the tuples that will be inserted into the view are calculated by the following two queries: "SELECT * FROM dR, S_pre" "SELECT * FROM R, dS" where S_pre is the table before the modification, R is the current state of table, that is, after the modification. This pre-update states of table is calculated by filtering inserted tuples and appending deleted tuples. The subquery that represents pre-update state is generated in get_prestate_rte(). Specifically, the insterted tuples are filtered by calling IVM_visible_in_prestate() in WHERE clause. This function checks the visibility of tuples by using the snapshot taken before table modification. The deleted tuples are contained in the old transition table, and this table is appended using UNION ALL. Transition tables for each modification are collected in each AFTER trigger function call. Then, the view maintenance is performed in the last call of the trigger. In the original PostgreSQL, tuplestores of transition tables are freed at the end of each nested query. However, their lifespan needs to be prolonged to the end of the out-most query in order to maintain the view in the last AFTER trigger. For this purpose, SetTransitionTablePreserved is added in trigger.c. ** Duplicate Tulpes When calculating changes that will occur in the view (= delta tables), multiplicity of tuples are calculated by using count(*). When deleting tuples from the view, tuples to be deleted are identified by joining the delta table with the view, and tuples are deleted as many as specified multiplicity by numbered using row_number() function. This is implemented in apply_old_delta(). When inserting tuples into the view, each tuple is duplicated to the specified multiplicity using generate_series() function. This is implemented in apply_new_delta(). ** DISTINCT clause When DISTINCT is used, the view has a hidden column __ivm_count__ that stores multiplicity for tuples. When tuples are deleted from or inserted into the view, the values of __ivm_count__ column is decreased or increased as many as specified multiplicity. Eventually, when the values becomes zero, the corresponding tuple is deleted from the
