Fix #8799: BUGCHECK "decompression overran buffer (179)" when WITH LOCK clause is used#8803
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ilya071294 merged 1 commit intoFirebirdSQL:masterfrom Nov 17, 2025
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…hen WITH LOCK clause is used VIO_writelock creates new_rpb by copying from org_rpb which has rpb_delta flag set. new_rpb is passed to prepare_update. It creates a delta but its size exceeds the limit (1024) so the current version is stored as a regular record. The problem is that rpb_delta flag remains set for new_rpb, and then replace_record sets it in the header of the primary version. From this moment any attempt to get data of older versions fails.
hvlad
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Nov 17, 2025
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Yes, but that leaves open the possibility of facing a similar bug again, so I see it as a worse solution.
I thought about it and came to this logic: if |
hvlad
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Nov 17, 2025
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…CK clause is used (#8803) VIO_writelock creates new_rpb by copying from org_rpb which has rpb_delta flag set. new_rpb is passed to prepare_update. It creates a delta but its size exceeds the limit (1024) so the current version is stored as a regular record. The problem is that rpb_delta flag remains set for new_rpb, and then replace_record sets it in the header of the primary version. From this moment any attempt to get data of older versions fails.
ilya071294
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Nov 17, 2025
…CK clause is used (#8803) VIO_writelock creates new_rpb by copying from org_rpb which has rpb_delta flag set. new_rpb is passed to prepare_update. It creates a delta but its size exceeds the limit (1024) so the current version is stored as a regular record. The problem is that rpb_delta flag remains set for new_rpb, and then replace_record sets it in the header of the primary version. From this moment any attempt to get data of older versions fails.
ilya071294
added a commit
that referenced
this pull request
Nov 17, 2025
…CK clause is used (#8803) VIO_writelock creates new_rpb by copying from org_rpb which has rpb_delta flag set. new_rpb is passed to prepare_update. It creates a delta but its size exceeds the limit (1024) so the current version is stored as a regular record. The problem is that rpb_delta flag remains set for new_rpb, and then replace_record sets it in the header of the primary version. From this moment any attempt to get data of older versions fails.
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VIO_writelockcreatesnew_rpbby copying fromorg_rpbwhich hasrpb_deltaflag set.new_rpbis passed toprepare_update. It creates a delta but its size exceeds the limit (1024) so the current version is stored as a regular record. The problem is thatrpb_deltaflag remains set fornew_rpb, and thenreplace_recordsets it in the header of the primary version. From this moment any attempt to get data of older versions fails.The fix is to let
prepare_updateclearrpb_deltaflag fromnew_rpbjust before an attempt to generate a delta.