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https://issues.apache.org/jira/browse/PHOENIX-7032?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17772719#comment-17772719
]
ASF GitHub Bot commented on PHOENIX-7032:
-----------------------------------------
kadirozde commented on code in PR #1701:
URL: https://github.com/apache/phoenix/pull/1701#discussion_r1349388465
##########
phoenix-core/src/main/java/org/apache/phoenix/optimize/QueryOptimizer.java:
##########
@@ -197,17 +199,41 @@ private List<QueryPlan> getApplicablePlans(QueryPlan
dataPlan, PhoenixStatement
return Collections.singletonList(compiler.compile());
}
+ private static boolean isPartialIndexUsable(SelectStatement select,
QueryPlan dataPlan,
+ PTable index) throws SQLException {
+
+ StatementContext context = new StatementContext(dataPlan.getContext());
+ context.setResolver(FromCompiler.getResolver(dataPlan.getTableRef()));
+ return WhereCompiler.contains(
+
index.getIndexWhereExpression(dataPlan.getContext().getConnection()),
+ WhereCompiler.transformDNF(select.getWhere(), context));
+ }
+
private List<QueryPlan> getApplicablePlansForSingleFlatQuery(QueryPlan
dataPlan, PhoenixStatement statement, List<? extends PDatum> targetColumns,
ParallelIteratorFactory parallelIteratorFactory, boolean stopAtBestPlan) throws
SQLException {
SelectStatement select = (SelectStatement)dataPlan.getStatement();
// Exit early if we have a point lookup as we can't get better than
that
if (dataPlan.getContext().getScanRanges().isPointLookup() &&
stopAtBestPlan && dataPlan.isApplicable()) {
return Collections.<QueryPlan> singletonList(dataPlan);
}
-
- List<PTable>indexes =
Lists.newArrayList(dataPlan.getTableRef().getTable().getIndexes());
- if (dataPlan.isApplicable() && (indexes.isEmpty() ||
dataPlan.isDegenerate() || dataPlan.getTableRef().hasDynamicCols() ||
select.getHint().hasHint(Hint.NO_INDEX))) {
+ List<PTable> indexList =
dataPlan.getTableRef().getTable().getIndexes();
+ if (dataPlan.isApplicable() &&
+ (indexList.isEmpty() ||
+ dataPlan.isDegenerate() ||
+ dataPlan.getTableRef().hasDynamicCols() ||
+ select.getHint().hasHint(Hint.NO_INDEX))) {
return Collections.<QueryPlan> singletonList(dataPlan);
}
+ // Include full indexes, and usable partial indexes
+ List<PTable> indexes = new ArrayList<>(indexList.size());
+ for (PTable index : indexList) {
+ if (index.getIndexWhere() != null) {
+ if (isPartialIndexUsable(select, dataPlan, index)) {
Review Comment:
Good suggestion!
> 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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