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https://issues.apache.org/jira/browse/PHOENIX-7032?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17782397#comment-17782397
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ASF GitHub Bot commented on PHOENIX-7032:
-----------------------------------------
kadirozde commented on PR #1701:
URL: https://github.com/apache/phoenix/pull/1701#issuecomment-1791860357
> The following index does not generate any index rows -
>
> CREATE TABLE IF NOT EXISTS S.T1(OID CHAR(15) NOT NULL,KP CHAR(3) NOT NULL,
ID1 INTEGER, ID2 VARCHAR, ID3 INTEGER, ROW_ID CHAR(15), COL1 VARCHAR, COL2
VARCHAR, CREATED_DATE DATE,CREATED_BY CHAR(15),LAST_UPDATE DATE,LAST_UPDATE_BY
CHAR(15),SYSTEM_MODSTAMP DATE CONSTRAINT pk PRIMARY KEY (OID,KP))
MULTI_TENANT=true,COLUMN_ENCODED_BYTES=0;
>
> CREATE INDEX IF NOT EXISTS P_T1_COL1_2_NOT_NULL_INDEX ON S.T1 (KP, COL1,
COL2) INCLUDE (ID1, ID2, ID3) WHERE COL1 IS NOT NULL AND COL2 IS NOT NULL;
>
> UPSERT INTO S.T1(OID, KP, CREATED_DATE, ID1, ID2, ID3, ROW_ID, COL1, COL2,
SYSTEM_MODSTAMP) VALUES('00D0x0000000001', '001', now(), 12200, 'id1-0001',
14566, '00R0r0000000001', 'col1-0001', 'col2-0001', now());
>
> Similar behavior for the following index CREATE INDEX IF NOT EXISTS
P_T1_ID2_COL1_NOT_NULL_INDEX ON S.T1 (KP, COL1, COL2) INCLUDE (ID1, ID2, ID3)
WHERE ID2 = 'id1-0001' AND COL1 IS NOT NULL;
Great catch @jpisaac ! The list of cells are searched using a binary search
during expression evaluation and thus they need to be sorted before evaluated.
I have just fixed it.
> Partial Global Secondary Indexes
> --------------------------------
>
> Key: PHOENIX-7032
> URL: https://issues.apache.org/jira/browse/PHOENIX-7032
> Project: Phoenix
> Issue Type: New Feature
> Reporter: Kadir Ozdemir
> Assignee: Kadir Ozdemir
> Priority: Major
>
> The secondary indexes supported in Phoenix have been full indexes such that
> for every data table row there is an index row. Generating an index row for
> every data table row is not always required. For example, some use cases do
> not require index rows for the data table rows in which indexed column values
> are null. Such indexes are called sparse indexes. Partial indexes generalize
> the concept of sparse indexing and allow users to specify the subset of the
> data table rows for which index rows will be maintained. This subset is
> specified using a WHERE clause added to the CREATE INDEX DDL statement.
> Partial secondary indexes were first proposed by Michael Stonebraker
> [here|https://dsf.berkeley.edu/papers/ERL-M89-17.pdf]. Since then several SQL
> databases (e.g.,
> [Postgres|https://www.postgresql.org/docs/current/indexes-partial.html] and
> [SQLite|https://www.sqlite.org/partialindex.html]) and NoSQL databases
> (e.g., [MongoDB|https://www.mongodb.com/docs/manual/core/index-partial/])
> have supported some form of partial indexes. It is challenging to allow
> arbitrary WHERE clauses in DDL statements. For example, Postgres does not
> allow subqueries in these where clauses and SQLite supports much more
> restrictive where clauses.
> Supporting arbitrary where clauses creates challenges for query optimizers in
> deciding the usability of a partial index for a given query. If the set of
> data table rows that satisfy the query is a subset of the data table rows
> that the partial index points back, then the query can use the index. Thus,
> the query optimizer has to decide if the WHERE clause of the query implies
> the WHERE clause of the index.
> Michael Stonebraker [here|https://dsf.berkeley.edu/papers/ERL-M89-17.pdf]
> suggests that an index WHERE clause is a conjunct of simple terms, i.e:
> i-clause-1 and i-clause-2 and ... and i-clause-m where each clause is of the
> form <column> <operator> <constant>. Hence, the qualification can be
> evaluated for each tuple in the indicated relation without consulting
> additional tuples.
> Phoenix partial indexes will initially support a more general set of index
> WHERE clauses that can be evaluated on a single row with the following
> exceptions
> * Subqueries are not allowed.
> * Like expressions are allowed with very limited support such that an index
> WHERE clause with like expressions can imply/contain a query if the query has
> the same like expressions that the index WHERE clause has.
> * Comparison between columns are allowed without supporting transitivity,
> for example, a > b and b > c does not imply a > c.
> Partial indexes will be supported initially for global secondary indexes,
> i.e., covered global indexes and uncovered global indexes. The local
> secondary indexes will be supported in future.
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