Merge pull request #4396 from yandex/attach-memory-limit-exceeded

Avoid "Memory limit exceeded" during ATTACH TABLE query

dbms/src/Storages/MergeTree/MergeTreeDataPart.cpp

@@ -460,6 +460,11 @@ void MergeTreeDataPart::makeCloneInDetached(const String & prefix) const
 
 void MergeTreeDataPart::loadColumnsChecksumsIndexes(bool require_columns_checksums, bool check_consistency)
 {
+    /// Memory should not be limited during ATTACH TABLE query.
+    /// This is already true at the server startup but must be also ensured for manual table ATTACH.
+    /// Motivation: memory for index is shared between queries - not belong to the query itself.
+    auto temporarily_disable_memory_tracker = getCurrentMemoryTrackerActionLock();
+
     loadColumns(require_columns_checksums);
     loadChecksums(require_columns_checksums);
     loadIndex();

dbms/tests/queries/0_stateless/00899_attach_memory_limit.reference

+10000000
+10000000

dbms/tests/queries/0_stateless/00899_attach_memory_limit.sql

+DROP TABLE IF EXISTS test.index_memory;
+CREATE TABLE test.index_memory (x UInt64) ENGINE = MergeTree ORDER BY x SETTINGS index_granularity = 1;
+INSERT INTO test.index_memory SELECT * FROM system.numbers LIMIT 10000000;
+SELECT count() FROM test.index_memory;
+DETACH TABLE test.index_memory;
+SET max_memory_usage = 79000000;
+ATTACH TABLE test.index_memory;
+SELECT count() FROM test.index_memory;
+DROP TABLE test.index_memory;