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!489 [I2AJVX] Update to Table Pushdown to handle incorrect stats from column's distinct value count 

Merge pull request !489 from SiddharthJaiswal/task-tablepushdown-userhint
This commit is contained in:
i-robot 2020-12-24 13:31:18 +08:00 committed by Gitee
parent 1085b97b06 3a1a9162c0
commit 6fc9377565
1 changed files with 13 additions and 12 deletions
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25
presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/TablePushdown.java
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@ -226,21 +226,22 @@ public class TablePushdown
TableHandle tableHandle = tableNode.getTable();
TableStatistics tableStatistics = metadata.getTableStatistics(ruleContext.getSession(), tableHandle, Constraint.alwaysTrue());
if (tableStatistics != null) {
/*
* We check here if tablestats is null or not.
* If not null then proceed as follows.
* */
return isTableWithUniqueColumnTableStatistics(tableStatistics, tableHandle);
/*
* We check here if tablestats is null or not.
* If not null then check if the stats match as per requirement.
* */
if (tableStatistics != null && isTableWithUniqueColumnTableStatistics(tableStatistics, tableHandle)) {
return true;
}
else {
/*
* if table statistics are not available, check if user hint is available. If not, return false as nothing can be tested at this point.
* If user hint is available, check-
* If table name of the current table doesn't match with user hint, then return false;
* If it matches, then check if the user supplied column name is present in the join criteria. If it does, return true;
* Else, return false.
* */
* if table statistics are not available or due to approx stats doesn't match, check if user hint is available.
* If not, return false as nothing can be tested at this point.
* If user hint is available, check-
* If table name of the current table doesn't match with user hint, then return false;
* If it matches, then check if the user supplied column name is present in the join criteria. If it does, return true;
* Else, return false.
* */
if (uniqueColumnsPerTable.isEmpty()) {
return false;
}