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Key: CORE-1477
Type: Improvement Improvement
Status: Closed Closed
Resolution: Fixed
Priority: Minor Minor
Assignee: Dmitry Yemanov
Reporter: Kuznetsov Eugene
Votes: 0
Watchers: 2
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Firebird Core

Avoiding excessive memory consumption by undo-log after series of updates

Created: 19/Mar/07 11:11 PM   Updated: 23/Feb/11 12:05 PM
Component/s: Engine
Affects Version/s: 2.0.1, 2.1 Alpha 1, 2.1 Beta 1, 2.0.2
Fix Version/s: 2.5 Beta 1

Time Tracking:
Not Specified

File Attachments: 1. Zip Archive Test.zip (37 kB)

Issue Links:
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Target: 2.5.0


 Description  « Hide
Look at the example

Start Transaction: isc_tpb_consistency,isc_tpb_no_auto_undo,isc_tpb_nowait

execute procedure TEST3

-----Statistics-----
Reads = 5344
Writes = 5053
Fetches = 8499490
Marks = 2810214
CurrentMemory = 17139964
MaxMemory = 17840520
NumBuffers = 1000
-----Detail statistics-----
read_seq_count
TEST_TABLE2 = 1000000
update_count
TEST_TABLE2 = 1000000
-----End------

execute procedure TEST3

-----Statistics-----
Reads = 12200
Writes = 495276
Fetches = 15811015
Marks = 5306902
CurrentMemory = 17140460
MaxMemory = 716093252
NumBuffers = 1000
-----Detail statistics-----
read_seq_count
TEST_TABLE2 = 1000000
update_count
TEST_TABLE2 = 1000000
-----End------

Commit Transaction

TEST3 is a simple procedure with the single update statement into it.
During the second call of TEST3 memory consumption grows extensively (see MaxMemory), exceeding database size at least five times more.
It seems, undo-log code needs for optimization.

With best regards, Eugene

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Kuznetsov Eugene added a comment - 19/Mar/07 11:12 PM
Test database