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[PATCH] Compressed TOAST data corruption with REPACK CONCURRENTLY - Mailing list pgsql-hackers

From	SATYANARAYANA NARLAPURAM
Subject	[PATCH] Compressed TOAST data corruption with REPACK CONCURRENTLY
Date	April 16 09:13:42
Msg-id	CAHg+QDeXb9HM2VGKXQedyCp52GzajJK5KOUdNi6oLjsS0nerQw@mail.gmail.com Whole thread
Responses	Re: [PATCH] Compressed TOAST data corruption with REPACK CONCURRENTLY Re: [PATCH] Compressed TOAST data corruption with REPACK CONCURRENTLY
List	pgsql-hackers

Hi hackers,

restore_tuple() in repack.c uses SET_VARSIZE() to reconstruct the varlena header when

reading back external attributes from the spill file. In this process, looks like the flag

SET_VARSIZE_COMPRESSED is silently lost. Because of this, when REPACK CONCURRENTLY

run any concurrently updated column whose value was TOAST-compressed ends up with raw

compressed bytes behind an "uncompressed" header returning garbled data on subsequent reads.

It appears that existing tests are using random chars which are uncompressable.

Please find the attached 0001-Fix-restore_tuple-losing-varlena-compression-flag.patch to fix this.

Additionally I updated the existing repack_toast test to include the scenario I was talking about.

Thanks,

Satya

From: Jakub Wartak
Date: 16 April, 09:09:43
Subject: Re: Add errdetail() with PID and UID about source of termination signal

From: Álvaro Herrera
Date: 16 April, 09:26:06
Subject: Re: meson html:alias vs. html:custom