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* [PATCH 01/10] Allow alternate compression methods for wal_compression
@ 2021-02-27 04:03 Andrey Borodin <[email protected]>
0 siblings, 0 replies; 3+ messages in thread
From: Andrey Borodin @ 2021-02-27 04:03 UTC (permalink / raw)
TODO: bump XLOG_PAGE_MAGIC
---
doc/src/sgml/config.sgml | 17 +++++
src/backend/Makefile | 2 +-
src/backend/access/transam/xlog.c | 10 +++
src/backend/access/transam/xloginsert.c | 52 +++++++++++++--
src/backend/access/transam/xlogreader.c | 63 ++++++++++++++++++-
src/backend/utils/misc/guc.c | 11 ++++
src/backend/utils/misc/postgresql.conf.sample | 1 +
src/include/access/xlog.h | 1 +
src/include/access/xlog_internal.h | 8 +++
src/include/access/xlogreader.h | 1 +
src/include/access/xlogrecord.h | 9 +--
11 files changed, 163 insertions(+), 12 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index a218d78bef..7fb2a84626 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3072,6 +3072,23 @@ include_dir 'conf.d'
</listitem>
</varlistentry>
+ <varlistentry id="guc-wal-compression-method" xreflabel="wal_compression_method">
+ <term><varname>wal_compressionion_method</varname> (<type>enum</type>)
+ <indexterm>
+ <primary><varname>wal_compression_method</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ This parameter selects the compression method used to compress WAL when
+ <varname>wal_compression</varname> is enabled.
+ The supported methods are pglz and zlib.
+ The default value is <literal>pglz</literal>.
+ Only superusers can change this setting.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="guc-wal-init-zero" xreflabel="wal_init_zero">
<term><varname>wal_init_zero</varname> (<type>boolean</type>)
<indexterm>
diff --git a/src/backend/Makefile b/src/backend/Makefile
index 0da848b1fd..3af216ddfc 100644
--- a/src/backend/Makefile
+++ b/src/backend/Makefile
@@ -48,7 +48,7 @@ OBJS = \
LIBS := $(filter-out -lpgport -lpgcommon, $(LIBS)) $(LDAP_LIBS_BE) $(ICU_LIBS)
# The backend doesn't need everything that's in LIBS, however
-LIBS := $(filter-out -lz -lreadline -ledit -ltermcap -lncurses -lcurses, $(LIBS))
+LIBS := $(filter-out -lreadline -ledit -ltermcap -lncurses -lcurses, $(LIBS))
ifeq ($(with_systemd),yes)
LIBS += -lsystemd
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index f4d1ce5dea..15da91a8dd 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -99,6 +99,7 @@ bool EnableHotStandby = false;
bool fullPageWrites = true;
bool wal_log_hints = false;
bool wal_compression = false;
+int wal_compression_method = WAL_COMPRESSION_PGLZ;
char *wal_consistency_checking_string = NULL;
bool *wal_consistency_checking = NULL;
bool wal_init_zero = true;
@@ -180,6 +181,15 @@ const struct config_enum_entry recovery_target_action_options[] = {
{NULL, 0, false}
};
+/* Note that due to conditional compilation, offsets within the array are not static */
+const struct config_enum_entry wal_compression_options[] = {
+ {"pglz", WAL_COMPRESSION_PGLZ, false},
+#ifdef HAVE_LIBZ
+ {"zlib", WAL_COMPRESSION_ZLIB, false},
+#endif
+ {NULL, 0, false}
+};
+
/*
* Statistics for current checkpoint are collected in this global struct.
* Because only the checkpointer or a stand-alone backend can perform
diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/transam/xloginsert.c
index 7052dc245e..34e1227381 100644
--- a/src/backend/access/transam/xloginsert.c
+++ b/src/backend/access/transam/xloginsert.c
@@ -33,6 +33,10 @@
#include "storage/proc.h"
#include "utils/memutils.h"
+#ifdef HAVE_LIBZ
+#include <zlib.h>
+#endif
+
/* Buffer size required to store a compressed version of backup block image */
#define PGLZ_MAX_BLCKSZ PGLZ_MAX_OUTPUT(BLCKSZ)
@@ -113,7 +117,8 @@ static XLogRecData *XLogRecordAssemble(RmgrId rmid, uint8 info,
XLogRecPtr RedoRecPtr, bool doPageWrites,
XLogRecPtr *fpw_lsn, int *num_fpi);
static bool XLogCompressBackupBlock(char *page, uint16 hole_offset,
- uint16 hole_length, char *dest, uint16 *dlen);
+ uint16 hole_length, char *dest,
+ uint16 *dlen, WalCompression compression);
/*
* Begin constructing a WAL record. This must be called before the
@@ -630,11 +635,12 @@ XLogRecordAssemble(RmgrId rmid, uint8 info,
*/
if (wal_compression)
{
+ bimg.compression_method = wal_compression_method;
is_compressed =
XLogCompressBackupBlock(page, bimg.hole_offset,
cbimg.hole_length,
regbuf->compressed_page,
- &compressed_len);
+ &compressed_len, bimg.compression_method);
}
/*
@@ -827,7 +833,7 @@ XLogRecordAssemble(RmgrId rmid, uint8 info,
*/
static bool
XLogCompressBackupBlock(char *page, uint16 hole_offset, uint16 hole_length,
- char *dest, uint16 *dlen)
+ char *dest, uint16 *dlen, WalCompression compression)
{
int32 orig_len = BLCKSZ - hole_length;
int32 len;
@@ -853,12 +859,48 @@ XLogCompressBackupBlock(char *page, uint16 hole_offset, uint16 hole_length,
else
source = page;
+ switch (compression)
+ {
+ case WAL_COMPRESSION_PGLZ:
+ len = pglz_compress(source, orig_len, dest, PGLZ_strategy_default);
+ break;
+
+#ifdef HAVE_LIBZ
+ case WAL_COMPRESSION_ZLIB:
+ {
+ unsigned long len_l = PGLZ_MAX_BLCKSZ;
+ int ret;
+ ret = compress2((Bytef*)dest, &len_l, (Bytef*)source, orig_len, 1);
+ if (ret != Z_OK)
+ {
+ // XXX: using an interface other than compress() would allow giving a better error message
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("failed compressing zlib (%d)", ret)));
+ len_l = -1;
+ }
+ len = len_l;
+ break;
+ }
+#endif
+
+ default:
+ /*
+ * It should be impossible to get here for unsupported algorithms,
+ * which cannot be assigned if they're not enabled at compile time.
+ */
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("unknown compression method requested: %d(%s)",
+ compression, wal_compression_name(compression))));
+
+ }
+
/*
- * We recheck the actual size even if pglz_compress() reports success and
+ * We recheck the actual size even if compression reports success and
* see if the number of bytes saved by compression is larger than the
* length of extra data needed for the compressed version of block image.
*/
- len = pglz_compress(source, orig_len, dest, PGLZ_strategy_default);
if (len >= 0 &&
len + extra_bytes < orig_len)
{
diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index 42738eb940..afca22a26c 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -33,6 +33,10 @@
#include "utils/memutils.h"
#endif
+#ifdef HAVE_LIBZ
+#include <zlib.h>
+#endif
+
static void report_invalid_record(XLogReaderState *state, const char *fmt,...)
pg_attribute_printf(2, 3);
static bool allocate_recordbuf(XLogReaderState *state, uint32 reclength);
@@ -1286,6 +1290,7 @@ DecodeXLogRecord(XLogReaderState *state, XLogRecord *record, char **errormsg)
{
COPY_HEADER_FIELD(&blk->bimg_len, sizeof(uint16));
COPY_HEADER_FIELD(&blk->hole_offset, sizeof(uint16));
+ COPY_HEADER_FIELD(&blk->compression_method, sizeof(uint8));
COPY_HEADER_FIELD(&blk->bimg_info, sizeof(uint8));
blk->apply_image = ((blk->bimg_info & BKPIMAGE_APPLY) != 0);
@@ -1535,6 +1540,29 @@ XLogRecGetBlockData(XLogReaderState *record, uint8 block_id, Size *len)
}
}
+/*
+ * Return a statically allocated string associated with the given compression
+ * method. This is similar to the guc, but isn't subject to conditional
+ * compilation.
+ */
+const char *
+wal_compression_name(WalCompression compression)
+{
+ /*
+ * This could index into the guc array, except that it's compiled
+ * conditionally and unsupported methods are elided.
+ */
+ switch (compression)
+ {
+ case WAL_COMPRESSION_PGLZ:
+ return "pglz";
+ case WAL_COMPRESSION_ZLIB:
+ return "zlib";
+ default:
+ return "???";
+ }
+}
+
/*
* Restore a full-page image from a backup block attached to an XLOG record.
*
@@ -1558,8 +1586,39 @@ RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page)
if (bkpb->bimg_info & BKPIMAGE_IS_COMPRESSED)
{
/* If a backup block image is compressed, decompress it */
- if (pglz_decompress(ptr, bkpb->bimg_len, tmp.data,
- BLCKSZ - bkpb->hole_length, true) < 0)
+ int32 decomp_result = -1;
+ switch (bkpb->compression_method)
+ {
+ case WAL_COMPRESSION_PGLZ:
+ decomp_result = pglz_decompress(ptr, bkpb->bimg_len, tmp.data,
+ BLCKSZ - bkpb->hole_length, true);
+ break;
+
+#ifdef HAVE_LIBZ
+ case WAL_COMPRESSION_ZLIB:
+ {
+ unsigned long decomp_result_l;
+ decomp_result_l = BLCKSZ - bkpb->hole_length;
+ if (uncompress((Bytef*)tmp.data, &decomp_result_l,
+ (Bytef*)ptr, bkpb->bimg_len) == Z_OK)
+ decomp_result = decomp_result_l;
+ else
+ decomp_result = -1;
+ break;
+ }
+#endif
+
+ default:
+ report_invalid_record(record, "image at %X/%X is compressed with unsupported codec, block %d (%d/%s)",
+ (uint32) (record->ReadRecPtr >> 32),
+ (uint32) record->ReadRecPtr,
+ block_id,
+ bkpb->compression_method,
+ wal_compression_name(bkpb->compression_method));
+ return false;
+ }
+
+ if (decomp_result < 0)
{
report_invalid_record(record, "invalid compressed image at %X/%X, block %d",
LSN_FORMAT_ARGS(record->ReadRecPtr),
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 855076b1fd..8084027465 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -508,6 +508,7 @@ extern const struct config_enum_entry archive_mode_options[];
extern const struct config_enum_entry recovery_target_action_options[];
extern const struct config_enum_entry sync_method_options[];
extern const struct config_enum_entry dynamic_shared_memory_options[];
+extern const struct config_enum_entry wal_compression_options[];
/*
* GUC option variables that are exported from this module
@@ -4721,6 +4722,16 @@ static struct config_enum ConfigureNamesEnum[] =
NULL, NULL, NULL
},
+ {
+ {"wal_compression_method", PGC_SIGHUP, WAL_SETTINGS,
+ gettext_noop("Set the method used to compress full page images in the WAL."),
+ NULL
+ },
+ &wal_compression_method,
+ WAL_COMPRESSION_PGLZ, wal_compression_options,
+ NULL, NULL, NULL
+ },
+
{
{"dynamic_shared_memory_type", PGC_POSTMASTER, RESOURCES_MEM,
gettext_noop("Selects the dynamic shared memory implementation used."),
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index f46c2dd7a8..ef69a94492 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -213,6 +213,7 @@
# open_sync
#full_page_writes = on # recover from partial page writes
#wal_compression = off # enable compression of full-page writes
+#wal_compression_method = pglz # pglz, zlib
#wal_log_hints = off # also do full page writes of non-critical updates
# (change requires restart)
#wal_init_zero = on # zero-fill new WAL files
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 6d384d3ce6..fa2e5c611f 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -117,6 +117,7 @@ extern bool EnableHotStandby;
extern bool fullPageWrites;
extern bool wal_log_hints;
extern bool wal_compression;
+extern int wal_compression_method;
extern bool wal_init_zero;
extern bool wal_recycle;
extern bool *wal_consistency_checking;
diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h
index b23e286406..d653839b97 100644
--- a/src/include/access/xlog_internal.h
+++ b/src/include/access/xlog_internal.h
@@ -324,4 +324,12 @@ extern bool InArchiveRecovery;
extern bool StandbyMode;
extern char *recoveryRestoreCommand;
+typedef enum WalCompression
+{
+ WAL_COMPRESSION_PGLZ,
+ WAL_COMPRESSION_ZLIB,
+} WalCompression;
+
+extern const char *wal_compression_name(WalCompression compression);
+
#endif /* XLOG_INTERNAL_H */
diff --git a/src/include/access/xlogreader.h b/src/include/access/xlogreader.h
index 21d200d3df..3d19c315d7 100644
--- a/src/include/access/xlogreader.h
+++ b/src/include/access/xlogreader.h
@@ -133,6 +133,7 @@ typedef struct
bool apply_image; /* has image that should be restored */
char *bkp_image;
uint16 hole_offset;
+ uint8 compression_method;
uint16 hole_length;
uint16 bimg_len;
uint8 bimg_info;
diff --git a/src/include/access/xlogrecord.h b/src/include/access/xlogrecord.h
index 80c92a2498..0d4c212f15 100644
--- a/src/include/access/xlogrecord.h
+++ b/src/include/access/xlogrecord.h
@@ -114,7 +114,7 @@ typedef struct XLogRecordBlockHeader
* present is (BLCKSZ - <length of "hole" bytes>).
*
* Additionally, when wal_compression is enabled, we will try to compress full
- * page images using the PGLZ compression algorithm, after removing the "hole".
+ * page images, after removing the "hole".
* This can reduce the WAL volume, but at some extra cost of CPU spent
* on the compression during WAL logging. In this case, since the "hole"
* length cannot be calculated by subtracting the number of page image bytes
@@ -129,9 +129,10 @@ typedef struct XLogRecordBlockHeader
*/
typedef struct XLogRecordBlockImageHeader
{
- uint16 length; /* number of page image bytes */
- uint16 hole_offset; /* number of bytes before "hole" */
- uint8 bimg_info; /* flag bits, see below */
+ uint16 length; /* number of page image bytes */
+ uint16 hole_offset; /* number of bytes before "hole" */
+ uint8 compression_method; /* compression method used for image */
+ uint8 bimg_info; /* flag bits, see below */
/*
* If BKPIMAGE_HAS_HOLE and BKPIMAGE_IS_COMPRESSED, an
--
2.17.0
--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="0002-Run-011_crash_recovery.pl-with-wal_level-minimal.patch"
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Set enable_seqscan doesn't take effect?
@ 2023-09-28 07:38 jacktby jacktby <[email protected]>
0 siblings, 1 reply; 3+ messages in thread
From: jacktby jacktby @ 2023-09-28 07:38 UTC (permalink / raw)
To: [email protected]; +Cc: [email protected]
> 2023年9月28日 01:07，Andres Freund <[email protected]> 写道：
>
> Hi,
>
> On 2023-09-28 00:37:41 +0800, jacktby jacktby wrote:
>> postgres=# SET enable_seqscan = off;
>> SET
>> postgres=# explain select * from t;
>> QUERY PLAN
>> -------------------------------------------------------------------------
>> Seq Scan on t (cost=10000000000.00..10000000023.60 rows=1360 width=32)
>> (1 row)
>>
>> postgres=# select * from t;
>> a
>> -------
>> [1,2]
>> (1 row)
>
> Sorry to be the grump here:
>
> You start several threads a week, often clearly not having done much, if any,
> prior research. Often even sending the same question to multiple lists. It
> should not be hard to find an explanation for the behaviour you see here.
>
> pgsql-hackers isn't a "do my work for me service". We're hacking on
> postgres. It's fine to occasionally ask for direction, but you're very clearly
> exceeding that.
>
> Greetings,
>
> Andres Freund
I’m so sorry for that. I think I’m not very familiar with pg, so I ask many naive questions. And I apologize for my behavior.
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Set enable_seqscan doesn't take effect?
@ 2023-09-28 13:57 Bruce Momjian <[email protected]>
parent: jacktby jacktby <[email protected]>
0 siblings, 0 replies; 3+ messages in thread
From: Bruce Momjian @ 2023-09-28 13:57 UTC (permalink / raw)
To: jacktby jacktby <[email protected]>; +Cc: [email protected]; [email protected]
On Thu, Sep 28, 2023 at 03:38:28PM +0800, jacktby jacktby wrote:
> > You start several threads a week, often clearly not having done much, if any,
> > prior research. Often even sending the same question to multiple lists. It
> > should not be hard to find an explanation for the behaviour you see here.
> >
> > pgsql-hackers isn't a "do my work for me service". We're hacking on
> > postgres. It's fine to occasionally ask for direction, but you're very clearly
> > exceeding that.
> >
> > Greetings,
> >
> > Andres Freund
> I’m so sorry for that. I think I’m not very familiar with pg, so I ask many naive questions. And I apologize for my behavior.
I think you might find our IRC channel a more natural fit for getting
your questions answered:
https://www.postgresql.org/community/irc/
--
Bruce Momjian <[email protected]> https://momjian.us
EDB https://enterprisedb.com
Only you can decide what is important to you.
^ permalink raw reply [nested|flat] 3+ messages in thread
end of thread, other threads:[~2023-09-28 13:57 UTC | newest]
Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2021-02-27 04:03 [PATCH 01/10] Allow alternate compression methods for wal_compression Andrey Borodin <[email protected]>
2023-09-28 07:38 Re: Set enable_seqscan doesn't take effect? jacktby jacktby <[email protected]>
2023-09-28 13:57 ` Re: Set enable_seqscan doesn't take effect? Bruce Momjian <[email protected]>
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