thevar1able/ClickHouse
1
0
Fork 0
mirror of https://github.com/ClickHouse/ClickHouse.git synced 2024-09-21 17:20:50 +00:00
Code Issues Packages Projects Releases Wiki Activity

allow to move conditions to prewhere with compact parts

Browse Source
This commit is contained in:
Anton Popov 2020-11-23 21:27:59 +03:00
parent e76f7c316b
commit 852a08eacb
3 changed files with 24 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
src/Storages/MergeTree/MergeTreeWhereOptimizer.cpp
View File

@ -147,9 +147,7 @@ void MergeTreeWhereOptimizer::analyzeImpl(Conditions & res, const ASTPtr & node)
/// Only table columns are considered. Not array joined columns. NOTE We're assuming that aliases was expanded.
&& isSubsetOfTableColumns(cond.identifiers)
/// Do not move conditions involving all queried columns.
&& cond.identifiers.size() < queried_columns.size()
/// Columns size of compact parts can't be counted. If all parts are compact do not move any condition.
&& cond.columns_size > 0;
&& cond.identifiers.size() < queried_columns.size();
if (cond.viable)
cond.good = isConditionGood(node);
@ -197,12 +195,14 @@ void MergeTreeWhereOptimizer::optimize(ASTSelectQuery & select) const
Conditions prewhere_conditions;
UInt64 total_size_of_moved_conditions = 0;
UInt64 total_number_of_moved_columns = 0;
/// Move condition and all other conditions depend on the same set of columns.
auto move_condition = [&](Conditions::iterator cond_it)
{
prewhere_conditions.splice(prewhere_conditions.end(), where_conditions, cond_it);
total_size_of_moved_conditions += cond_it->columns_size;
total_number_of_moved_columns += cond_it->identifiers.size();
/// Move all other viable conditions that depend on the same set of columns.
for (auto jt = where_conditions.begin(); jt != where_conditions.end();)
@ -225,7 +225,15 @@ void MergeTreeWhereOptimizer::optimize(ASTSelectQuery & select) const
break;
/// 10% ratio is just a guess.
if (total_size_of_moved_conditions > 0 && (total_size_of_moved_conditions + it->columns_size) * 10 > total_size_of_queried_columns)
/// If sizes of compressed columns cannot be calculated, e.g. for compact parts,
/// use number of moved columns as a fallback.
bool moved_enough =
(total_size_of_queried_columns > 0 && total_size_of_moved_conditions > 0
&& (total_size_of_moved_conditions + it->columns_size) * 10 > total_size_of_queried_columns)
|| (total_number_of_moved_columns > 0
&& (total_number_of_moved_columns + it->identifiers.size()) * 10 > queried_columns.size());
if (moved_enough)
break;
move_condition(it);

5
tests/queries/0_stateless/01582_move_to_prewhere_compact_parts.reference Normal file
View File

@ -0,0 +1,5 @@
SELECT
x,
y
FROM prewhere_move
PREWHERE x > 100

7
tests/queries/0_stateless/01582_move_to_prewhere_compact_parts.sql Normal file
View File

@ -0,0 +1,7 @@
DROP TABLE IF EXISTS prewhere_move;
CREATE TABLE prewhere_move (x Int, y String) ENGINE = MergeTree ORDER BY tuple();
INSERT INTO prewhere_move SELECT number, toString(number) FROM numbers(1000);
EXPLAIN SYNTAX SELECT * FROM prewhere_move WHERE x > 100;
DROP TABLE prewhere_move;