From e9d19c48cf112a46ae9dead51c16d734b5bf79e8 Mon Sep 17 00:00:00 2001 From: Tomas Vondra Date: Tue, 30 Sep 2025 02:24:20 +0200 Subject: [PATCH v20251001 19/25] remember compression method for each file Otherwise we might have a problem if the compression method changes during lifetime of a file, e.g. with an open cursor. Example: set temp_file_compression = 'lz4'; set work_mem = '1MB'; begin; declare c no scroll cursor for select i from generate_series(1,10000000) s(i); fetch 10000 from c; set temp_file_compression = 'pglz'; fetch 10000 from c; This ends with ERROR: compressed data is corrupt --- src/backend/storage/file/buffile.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/src/backend/storage/file/buffile.c b/src/backend/storage/file/buffile.c index cb6763ed586..e759e6687b6 100644 --- a/src/backend/storage/file/buffile.c +++ b/src/backend/storage/file/buffile.c @@ -73,6 +73,9 @@ #define MAX_PHYSICAL_FILESIZE 0x40000000 #define BUFFILE_SEG_SIZE (MAX_PHYSICAL_FILESIZE / BLCKSZ) +/* + * Optional transparent compression of temporary files. Disaled by default. + */ int temp_file_compression = TEMP_NONE_COMPRESSION; /* @@ -115,7 +118,7 @@ struct BufFile */ PGAlignedBlock buffer; - bool compress; /* State of usage file compression */ + int compress; /* enabled compression for the file */ char *cBuffer; /* compression buffer */ }; @@ -160,7 +163,7 @@ makeBufFileCommon(int nfiles) file->curOffset = 0; file->pos = 0; file->nbytes = 0; - file->compress = false; + file->compress = TEMP_NONE_COMPRESSION; file->cBuffer = NULL; return file; @@ -322,7 +325,7 @@ BufFileCreateCompressTemp(bool interXact) allocated_size = size; } - file->compress = true; + file->compress = temp_file_compression; file->cBuffer = buff; } @@ -572,7 +575,7 @@ BufFileLoadBuffer(BufFile *file) else INSTR_TIME_SET_ZERO(io_start); - if (!file->compress) + if (file->compress == TEMP_NONE_COMPRESSION) { /* * Read whatever we can get, up to a full bufferload. @@ -676,7 +679,7 @@ BufFileLoadBuffer(BufFile *file) FilePathName(thisfile)))); } - switch (temp_file_compression) + switch (file->compress) { case TEMP_LZ4_COMPRESSION: #ifdef USE_LZ4 @@ -745,7 +748,7 @@ BufFileDumpBuffer(BufFile *file) * XXX I'm not 100% happy with all the variables here, there seems to be * more than necessary. */ - if (file->compress) + if (file->compress != TEMP_NONE_COMPRESSION) { char *cData; int cSize = 0; @@ -758,7 +761,7 @@ BufFileDumpBuffer(BufFile *file) header.len = -1; header.raw_len = nbytesOriginal; - switch (temp_file_compression) + switch (file->compress) { case TEMP_LZ4_COMPRESSION: { -- 2.51.0