From dd6fdc06513698567e374c02bd2e631d2519807f Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Thu, 22 Apr 2021 23:08:30 +0300
Subject: [PATCH 1/7] Resolve issue#5: store update_lsn of each block into two
independent slots.
Previously we thought that 1 MB can track changes page-to-page in the 1 GB of
data files. However, recently it became evident that our ptrack map or basic
hash table behaves more like a Bloom filter with a number of hash functions k = 1.
See more here: https://en.wikipedia.org/wiki/Bloom_filter#Probability_of_false_positives.
Such filter has naturally more collisions.
By storing update_lsn of each block in the additional slot we perform as
a Bloom filter with k = 2, which significatly reduces collision rate.
---
engine.c | 95 +++++++++++++++++++++++++++++++++-----------------------
engine.h | 8 ++---
ptrack.c | 31 +++++++++++++-----
ptrack.h | 2 +-
4 files changed, 85 insertions(+), 51 deletions(-)
diff --git a/engine.c b/engine.c
index 35cc14c..c8085a0 100644
--- a/engine.c
+++ b/engine.c
@@ -156,6 +156,8 @@ ptrackMapInit(void)
sprintf(ptrack_path, "%s/%s", DataDir, PTRACK_PATH);
sprintf(ptrack_mmap_path, "%s/%s", DataDir, PTRACK_MMAP_PATH);
+ptrack_map_reinit:
+
/* Remove old PTRACK_MMAP_PATH file, if exists */
if (ptrack_file_exists(ptrack_mmap_path))
durable_unlink(ptrack_mmap_path, LOG);
@@ -175,18 +177,15 @@ ptrackMapInit(void)
if (stat(ptrack_path, &stat_buf) == 0)
{
copy_file(ptrack_path, ptrack_mmap_path);
- is_new_map = false; /* flag to check checksum */
+ is_new_map = false; /* flag to check map file format and checksum */
ptrack_fd = BasicOpenFile(ptrack_mmap_path, O_RDWR | PG_BINARY);
- if (ptrack_fd < 0)
- elog(ERROR, "ptrack init: failed to open map file \"%s\": %m", ptrack_mmap_path);
}
else
- {
/* Create new file for PTRACK_MMAP_PATH */
ptrack_fd = BasicOpenFile(ptrack_mmap_path, O_RDWR | O_CREAT | PG_BINARY);
- if (ptrack_fd < 0)
- elog(ERROR, "ptrack init: failed to open map file \"%s\": %m", ptrack_mmap_path);
- }
+
+ if (ptrack_fd < 0)
+ elog(ERROR, "ptrack init: failed to open map file \"%s\": %m", ptrack_mmap_path);
#ifdef WIN32
{
@@ -227,7 +226,19 @@ ptrackMapInit(void)
elog(ERROR, "ptrack init: wrong map format of file \"%s\"", ptrack_path);
/* Check ptrack version inside old ptrack map */
- /* No-op for now, but may be used for future compatibility checks */
+ if (ptrack_map->version_num != PTRACK_VERSION_NUM)
+ {
+ ereport(WARNING,
+ (errcode(ERRCODE_DATA_CORRUPTED),
+ errmsg("ptrack init: map format version %d in the file \"%s\" is incompatible with loaded version %d",
+ ptrack_map->version_num, ptrack_path, PTRACK_VERSION_NUM),
+ errdetail("Deleting file \"%s\" and reinitializing ptrack map.", ptrack_path)));
+
+ /* Delete and try again */
+ durable_unlink(ptrack_path, LOG);
+ is_new_map = true;
+ goto ptrack_map_reinit;
+ }
/* Check CRC */
INIT_CRC32C(crc);
@@ -641,48 +652,56 @@ void
ptrack_mark_block(RelFileNodeBackend smgr_rnode,
ForkNumber forknum, BlockNumber blocknum)
{
+ PtBlockId bid;
size_t hash;
+ size_t slot1;
+ size_t slot2;
XLogRecPtr new_lsn;
- PtBlockId bid;
/*
* We use pg_atomic_uint64 here only for alignment purposes, because
- * pg_atomic_uint64 is forcely aligned on 8 bytes during the MSVC build.
+ * pg_atomic_uint64 is forcedly aligned on 8 bytes during the MSVC build.
*/
pg_atomic_uint64 old_lsn;
pg_atomic_uint64 old_init_lsn;
- if (ptrack_map_size != 0 && (ptrack_map != NULL) &&
- smgr_rnode.backend == InvalidBackendId) /* do not track temporary
- * relations */
- {
- bid.relnode = smgr_rnode.node;
- bid.forknum = forknum;
- bid.blocknum = blocknum;
- hash = BID_HASH_FUNC(bid);
-
- if (RecoveryInProgress())
- new_lsn = GetXLogReplayRecPtr(NULL);
- else
- new_lsn = GetXLogInsertRecPtr();
+ if (ptrack_map_size == 0
+ || ptrack_map == NULL
+ || smgr_rnode.backend != InvalidBackendId) /* do not track temporary
+ * relations */
+ return;
- old_lsn.value = pg_atomic_read_u64(&ptrack_map->entries[hash]);
+ bid.relnode = smgr_rnode.node;
+ bid.forknum = forknum;
+ bid.blocknum = blocknum;
- /* Atomically assign new init LSN value */
- old_init_lsn.value = pg_atomic_read_u64(&ptrack_map->init_lsn);
+ hash = BID_HASH_FUNC(bid);
+ slot1 = hash % PtrackContentNblocks;
+ slot2 = ((hash << 32) | (hash >> 32)) % PtrackContentNblocks;
- if (old_init_lsn.value == InvalidXLogRecPtr)
- {
- elog(DEBUG1, "ptrack_mark_block: init_lsn " UINT64_FORMAT " <- " UINT64_FORMAT, old_init_lsn.value, new_lsn);
-
- while (old_init_lsn.value < new_lsn &&
- !pg_atomic_compare_exchange_u64(&ptrack_map->init_lsn, (uint64 *) &old_init_lsn.value, new_lsn));
- }
+ if (RecoveryInProgress())
+ new_lsn = GetXLogReplayRecPtr(NULL);
+ else
+ new_lsn = GetXLogInsertRecPtr();
- elog(DEBUG3, "ptrack_mark_block: map[%zu]=" UINT64_FORMAT " <- " UINT64_FORMAT, hash, old_lsn.value, new_lsn);
+ /* Atomically assign new init LSN value */
+ old_init_lsn.value = pg_atomic_read_u64(&ptrack_map->init_lsn);
+ if (old_init_lsn.value == InvalidXLogRecPtr)
+ {
+ elog(DEBUG1, "ptrack_mark_block: init_lsn " UINT64_FORMAT " <- " UINT64_FORMAT, old_init_lsn.value, new_lsn);
- /* Atomically assign new LSN value */
- while (old_lsn.value < new_lsn &&
- !pg_atomic_compare_exchange_u64(&ptrack_map->entries[hash], (uint64 *) &old_lsn.value, new_lsn));
- elog(DEBUG3, "ptrack_mark_block: map[%zu]=" UINT64_FORMAT, hash, pg_atomic_read_u64(&ptrack_map->entries[hash]));
+ while (old_init_lsn.value < new_lsn &&
+ !pg_atomic_compare_exchange_u64(&ptrack_map->init_lsn, (uint64 *) &old_init_lsn.value, new_lsn));
}
+
+ /* Atomically assign new LSN value to the first slot */
+ old_lsn.value = pg_atomic_read_u64(&ptrack_map->entries[slot1]);
+ elog(DEBUG3, "ptrack_mark_block: map[%zu]=" UINT64_FORMAT " <- " UINT64_FORMAT, slot1, old_lsn.value, new_lsn);
+ while (old_lsn.value < new_lsn &&
+ !pg_atomic_compare_exchange_u64(&ptrack_map->entries[slot1], (uint64 *) &old_lsn.value, new_lsn));
+ elog(DEBUG3, "ptrack_mark_block: map[%zu]=" UINT64_FORMAT, hash, pg_atomic_read_u64(&ptrack_map->entries[slot1]));
+
+ /* And to the second */
+ old_lsn.value = pg_atomic_read_u64(&ptrack_map->entries[slot2]);
+ while (old_lsn.value < new_lsn &&
+ !pg_atomic_compare_exchange_u64(&ptrack_map->entries[slot2], (uint64 *) &old_lsn.value, new_lsn));
}
diff --git a/engine.h b/engine.h
index 34cf15f..e46f803 100644
--- a/engine.h
+++ b/engine.h
@@ -50,7 +50,7 @@ typedef struct PtrackMapHdr
{
/*
* Three magic bytes (+ \0) to be sure, that we are reading ptrack.map
- * with a right PtrackMapHdr strucutre.
+ * with a right PtrackMapHdr structure.
*/
char magic[PTRACK_MAGIC_SIZE];
@@ -72,7 +72,6 @@ typedef struct PtrackMapHdr
typedef PtrackMapHdr * PtrackMap;
-/* TODO: check MAXALIGN usage below */
/* Number of elements in ptrack map (LSN array) */
#define PtrackContentNblocks \
((ptrack_map_size - offsetof(PtrackMapHdr, entries) - sizeof(pg_crc32c)) / sizeof(pg_atomic_uint64))
@@ -84,9 +83,10 @@ typedef PtrackMapHdr * PtrackMap;
/* CRC32 value offset in order to directly access it in the mmap'ed memory chunk */
#define PtrackCrcOffset (PtrackActualSize - sizeof(pg_crc32c))
-/* Map block address 'bid' to map slot */
+/* Block address 'bid' to hash. To get slot position in map should be divided
+ * with '% PtrackContentNblocks' */
#define BID_HASH_FUNC(bid) \
- (size_t)(DatumGetUInt64(hash_any_extended((unsigned char *)&bid, sizeof(bid), 0)) % PtrackContentNblocks)
+ (size_t)(DatumGetUInt64(hash_any_extended((unsigned char *)&bid, sizeof(bid), 0)))
/*
* Per process pointer to shared ptrack_map
diff --git a/ptrack.c b/ptrack.c
index d897ecf..4992726 100644
--- a/ptrack.c
+++ b/ptrack.c
@@ -420,10 +420,9 @@ PG_FUNCTION_INFO_V1(ptrack_get_pagemapset);
Datum
ptrack_get_pagemapset(PG_FUNCTION_ARGS)
{
+ PtScanCtx *ctx;
FuncCallContext *funcctx;
- PtScanCtx *ctx;
MemoryContext oldcontext;
- XLogRecPtr update_lsn;
datapagemap_t pagemap;
char gather_path[MAXPGPATH];
@@ -486,6 +485,12 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
while (true)
{
+ size_t hash;
+ size_t slot1;
+ size_t slot2;
+ XLogRecPtr update_lsn1;
+ XLogRecPtr update_lsn2;
+
/* Stop traversal if there are no more segments */
if (ctx->bid.blocknum > ctx->relsize)
{
@@ -525,15 +530,25 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
}
}
- update_lsn = pg_atomic_read_u64(&ptrack_map->entries[BID_HASH_FUNC(ctx->bid)]);
+ hash = BID_HASH_FUNC(ctx->bid);
+ slot1 = hash % PtrackContentNblocks;
+ slot2 = ((hash << 32) | (hash >> 32)) % PtrackContentNblocks;
+
+ update_lsn1 = pg_atomic_read_u64(&ptrack_map->entries[slot1]);
+ update_lsn2 = pg_atomic_read_u64(&ptrack_map->entries[slot2]);
+
+ if (update_lsn1 != InvalidXLogRecPtr)
+ elog(DEBUG3, "ptrack: update_lsn1 %X/%X of blckno %u of file %s",
+ (uint32) (update_lsn1 >> 32), (uint32) update_lsn1,
+ ctx->bid.blocknum, ctx->relpath);
- if (update_lsn != InvalidXLogRecPtr)
- elog(DEBUG3, "ptrack: update_lsn %X/%X of blckno %u of file %s",
- (uint32) (update_lsn >> 32), (uint32) update_lsn,
+ if (update_lsn2 != InvalidXLogRecPtr)
+ elog(DEBUG3, "ptrack: update_lsn2 %X/%X of blckno %u of file %s",
+ (uint32) (update_lsn1 >> 32), (uint32) update_lsn2,
ctx->bid.blocknum, ctx->relpath);
- /* Block has been changed since specified LSN. Mark it in the bitmap */
- if (update_lsn >= ctx->lsn)
+ /* Block has been changed since specified LSN. Mark it in the bitmap */
+ if (update_lsn1 >= ctx->lsn && update_lsn2 >= ctx->lsn)
datapagemap_add(&pagemap, ctx->bid.blocknum % ((BlockNumber) RELSEG_SIZE));
ctx->bid.blocknum += 1;
diff --git a/ptrack.h b/ptrack.h
index 7e6b6e5..4375963 100644
--- a/ptrack.h
+++ b/ptrack.h
@@ -24,7 +24,7 @@
/* Ptrack version as a string */
#define PTRACK_VERSION "2.1"
/* Ptrack version as a number */
-#define PTRACK_VERSION_NUM 210
+#define PTRACK_VERSION_NUM 220
/*
* Structure identifying block on the disk.
From 829f96cf53131a0d57a31ff929ea8fd46fbeb09b Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Fri, 23 Apr 2021 00:12:27 +0300
Subject: [PATCH 2/7] Resolve issue#1: add ptrack_get_change_stat().
Also bump extversion to 2.2
---
.gitignore | 2 --
Makefile | 18 +++---------------
ptrack--2.1--2.2.sql | 29 +++++++++++++++++++++++++++++
ptrack.sql => ptrack--2.1.sql | 2 ++
ptrack.control | 2 +-
ptrack.h | 2 +-
t/001_basic.pl | 6 +++++-
7 files changed, 41 insertions(+), 20 deletions(-)
create mode 100644 ptrack--2.1--2.2.sql
rename ptrack.sql => ptrack--2.1.sql (94%)
diff --git a/.gitignore b/.gitignore
index b46b4ef..4990aa6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,4 @@
.deps
*.so
*.o
-ptrack--2.0.sql
Dockerfile
-
diff --git a/Makefile b/Makefile
index 8544f90..ba9ce1d 100644
--- a/Makefile
+++ b/Makefile
@@ -2,13 +2,11 @@
MODULE_big = ptrack
OBJS = ptrack.o datapagemap.o engine.o $(WIN32RES)
-EXTENSION = ptrack
-EXTVERSION = 2.1
-DATA = ptrack.sql ptrack--2.0--2.1.sql
-DATA_built = $(EXTENSION)--$(EXTVERSION).sql
PGFILEDESC = "ptrack - block-level incremental backup engine"
-EXTRA_CLEAN = $(EXTENSION)--$(EXTVERSION).sql
+EXTENSION = ptrack
+EXTVERSION = 2.2
+DATA = ptrack--2.1.sql ptrack--2.0--2.1.sql ptrack--2.1--2.2.sql
TAP_TESTS = 1
@@ -22,13 +20,3 @@ top_builddir = ../..
include $(top_builddir)/src/Makefile.global
include $(top_srcdir)/contrib/contrib-global.mk
endif
-
-$(EXTENSION)--$(EXTVERSION).sql: ptrack.sql
- cat $^ > $@
-
-# temp-install: EXTRA_INSTALL=contrib/ptrack
-
-# check-tap: temp-install
-# $(prove_check)
-
-# check: check-tap
diff --git a/ptrack--2.1--2.2.sql b/ptrack--2.1--2.2.sql
new file mode 100644
index 0000000..d666fc3
--- /dev/null
+++ b/ptrack--2.1--2.2.sql
@@ -0,0 +1,29 @@
+/* ptrack/ptrack--2.1--2.2.sql */
+
+-- Complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION ptrack UPDATE;" to load this file.\ quit
+
+CREATE FUNCTION ptrack_get_change_stat(start_lsn pg_lsn)
+ RETURNS TABLE (
+ files bigint,
+ pages bigint,
+ "size, MB" numeric
+ ) AS
+$func$
+DECLARE
+block_size bigint;
+BEGIN
+ block_size := (SELECT setting FROM pg_settings WHERE name = 'block_size');
+
+ RETURN QUERY
+ SELECT changed_files,
+ changed_pages,
+ block_size*changed_pages/(1024.0*1024)
+ FROM
+ (SELECT count(path) AS changed_files,
+ sum(
+ length(replace(right((pagemap)::text, -1)::varbit::text, '0', ''))
+ ) AS changed_pages
+ FROM ptrack_get_pagemapset(start_lsn)) s;
+END
+$func$ LANGUAGE plpgsql;
diff --git a/ptrack.sql b/ptrack--2.1.sql
similarity index 94%
rename from ptrack.sql
rename to ptrack--2.1.sql
index 80ae927..c963964 100644
--- a/ptrack.sql
+++ b/ptrack--2.1.sql
@@ -1,3 +1,5 @@
+/* ptrack/ptrack--2.1.sql */
+
-- Complain if script is sourced in psql, rather than via CREATE EXTENSION
\echo Use "CREATE EXTENSION ptrack" to load this file. \quit
diff --git a/ptrack.control b/ptrack.control
index d2d8792..ec0af9d 100644
--- a/ptrack.control
+++ b/ptrack.control
@@ -1,5 +1,5 @@
# ptrack extension
comment = 'block-level incremental backup engine'
-default_version = '2.1'
+default_version = '2.2'
module_pathname = '$libdir/ptrack'
relocatable = true
diff --git a/ptrack.h b/ptrack.h
index 4375963..d205115 100644
--- a/ptrack.h
+++ b/ptrack.h
@@ -22,7 +22,7 @@
#include "utils/relcache.h"
/* Ptrack version as a string */
-#define PTRACK_VERSION "2.1"
+#define PTRACK_VERSION "2.2"
/* Ptrack version as a number */
#define PTRACK_VERSION_NUM 220
diff --git a/t/001_basic.pl b/t/001_basic.pl
index 1abc788..bac81f2 100644
--- a/t/001_basic.pl
+++ b/t/001_basic.pl
@@ -10,7 +10,7 @@
use TestLib;
use Test::More;
-plan tests => 23;
+plan tests => 24;
my $node;
my $res;
@@ -115,6 +115,10 @@
qr/$rel_oid/,
'ptrack pagemapset should contain new relation oid');
+# Check change stats
+$res_stdout = $node->safe_psql("postgres", "SELECT pages FROM ptrack_get_change_stat('$flush_lsn')");
+is($res_stdout > 0, 1, 'should be able to get aggregated stats of changes');
+
# We should be able to change ptrack map size (but loose all changes)
$node->append_conf(
'postgresql.conf', q{
From 3026be92c398eeeb7bc8edf65ca0deef25c82c17 Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Wed, 12 May 2021 20:02:26 +0300
Subject: [PATCH 3/7] Add new function ptrack_get_change_file_stat(start_lsn
pg_lsn)
---
README.md | 8 +++++++-
ptrack--2.1--2.2.sql | 25 +++++++++++++++++++++++++
t/001_basic.pl | 5 ++++-
3 files changed, 36 insertions(+), 2 deletions(-)
diff --git a/README.md b/README.md
index 57a7c5c..06e4b18 100644
--- a/README.md
+++ b/README.md
@@ -65,7 +65,9 @@ To disable `ptrack` and clean up all remaining service files set `ptrack.map_siz
* ptrack_version() — returns ptrack version string.
* ptrack_init_lsn() — returns LSN of the last ptrack map initialization.
- * ptrack_get_pagemapset('LSN') — returns a set of changed data files with bitmaps of changed blocks since specified LSN.
+ * ptrack_get_pagemapset(start_lsn pg_lsn) — returns a set of changed data files with bitmaps of changed blocks since specified `start_lsn`.
+ * ptrack_get_change_stat(start_lsn pg_lsn) — returns statistic of changes (number of files, pages and size in MB) since specified `start_lsn`.
+ * ptrack_get_change_file_stat(start_lsn pg_lsn) — returns per file statistic of changes (number of pages and size in MB) since specified `start_lsn`.
Usage example:
@@ -102,6 +104,10 @@ Usually, you have to only install new version of `ptrack` and do `ALTER EXTENSIO
* Do `ALTER EXTENSION 'ptrack' UPDATE;`.
* Restart your server.
+#### Upgrading from 2.1.* to 2.2.*:
+
+Since version 2.2 we use a different algorithm for tracking changed pages. Thus, data recorded in the `ptrack.map` using pre 2.2 versions of `ptrack` is incompatible with newer versions. After extension upgrade and server restart old `ptrack.map` will be discarded with `WARNING` and initialized from the scratch.
+
## Limitations
1. You can only use `ptrack` safely with `wal_level >= 'replica'`. Otherwise, you can lose tracking of some changes if crash-recovery occurs, since [certain commands are designed not to write WAL at all if wal_level is minimal](https://www.postgresql.org/docs/12/populate.html#POPULATE-PITR), but we only durably flush `ptrack` map at checkpoint time.
diff --git a/ptrack--2.1--2.2.sql b/ptrack--2.1--2.2.sql
index d666fc3..2a0d97f 100644
--- a/ptrack--2.1--2.2.sql
+++ b/ptrack--2.1--2.2.sql
@@ -27,3 +27,28 @@ BEGIN
FROM ptrack_get_pagemapset(start_lsn)) s;
END
$func$ LANGUAGE plpgsql;
+
+CREATE FUNCTION ptrack_get_change_file_stat(start_lsn pg_lsn)
+ RETURNS TABLE (
+ file_path text,
+ pages int,
+ "size, MB" numeric
+ ) AS
+$func$
+DECLARE
+block_size bigint;
+BEGIN
+ block_size := (SELECT setting FROM pg_settings WHERE name = 'block_size');
+
+ RETURN QUERY
+ SELECT s.path,
+ changed_pages,
+ block_size*changed_pages/(1024.0*1024)
+ FROM
+ (SELECT path,
+ length(replace(right((pagemap)::text, -1)::varbit::text, '0', ''))
+ AS changed_pages
+ FROM ptrack_get_pagemapset(start_lsn)) s
+ ORDER BY (changed_pages, s.path) DESC;
+END
+$func$ LANGUAGE plpgsql;
diff --git a/t/001_basic.pl b/t/001_basic.pl
index bac81f2..37285d9 100644
--- a/t/001_basic.pl
+++ b/t/001_basic.pl
@@ -10,7 +10,7 @@
use TestLib;
use Test::More;
-plan tests => 24;
+plan tests => 25;
my $node;
my $res;
@@ -119,6 +119,9 @@
$res_stdout = $node->safe_psql("postgres", "SELECT pages FROM ptrack_get_change_stat('$flush_lsn')");
is($res_stdout > 0, 1, 'should be able to get aggregated stats of changes');
+$res_stdout = $node->safe_psql("postgres", "SELECT count(*) FROM ptrack_get_change_file_stat('$flush_lsn')");
+is($res_stdout > 0, 1, 'should be able to get per file stats of changes');
+
# We should be able to change ptrack map size (but loose all changes)
$node->append_conf(
'postgresql.conf', q{
From cf8e30962cf87afd9388f31428c895dd5b15278b Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Wed, 12 May 2021 20:33:42 +0300
Subject: [PATCH 4/7] Slightly optimize ptrack_get_pagemapset
Probe the second slot only if the first one succeded.
---
ptrack.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/ptrack.c b/ptrack.c
index 4992726..f2701af 100644
--- a/ptrack.c
+++ b/ptrack.c
@@ -532,24 +532,29 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
hash = BID_HASH_FUNC(ctx->bid);
slot1 = hash % PtrackContentNblocks;
- slot2 = ((hash << 32) | (hash >> 32)) % PtrackContentNblocks;
update_lsn1 = pg_atomic_read_u64(&ptrack_map->entries[slot1]);
- update_lsn2 = pg_atomic_read_u64(&ptrack_map->entries[slot2]);
if (update_lsn1 != InvalidXLogRecPtr)
elog(DEBUG3, "ptrack: update_lsn1 %X/%X of blckno %u of file %s",
(uint32) (update_lsn1 >> 32), (uint32) update_lsn1,
ctx->bid.blocknum, ctx->relpath);
- if (update_lsn2 != InvalidXLogRecPtr)
- elog(DEBUG3, "ptrack: update_lsn2 %X/%X of blckno %u of file %s",
- (uint32) (update_lsn1 >> 32), (uint32) update_lsn2,
- ctx->bid.blocknum, ctx->relpath);
+ /* Only probe the second slot if the first one is marked */
+ if (update_lsn1 >= ctx->lsn)
+ {
+ slot2 = ((hash << 32) | (hash >> 32)) % PtrackContentNblocks;
+ update_lsn2 = pg_atomic_read_u64(&ptrack_map->entries[slot2]);
- /* Block has been changed since specified LSN. Mark it in the bitmap */
- if (update_lsn1 >= ctx->lsn && update_lsn2 >= ctx->lsn)
- datapagemap_add(&pagemap, ctx->bid.blocknum % ((BlockNumber) RELSEG_SIZE));
+ if (update_lsn2 != InvalidXLogRecPtr)
+ elog(DEBUG3, "ptrack: update_lsn2 %X/%X of blckno %u of file %s",
+ (uint32) (update_lsn1 >> 32), (uint32) update_lsn2,
+ ctx->bid.blocknum, ctx->relpath);
+
+ /* Block has been changed since specified LSN. Mark it in the bitmap */
+ if (update_lsn2 >= ctx->lsn)
+ datapagemap_add(&pagemap, ctx->bid.blocknum % ((BlockNumber) RELSEG_SIZE));
+ }
ctx->bid.blocknum += 1;
}
From fbfba8c73bce64e176dadb3b66cb0576a20ebe59 Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Thu, 13 May 2021 18:56:41 +0300
Subject: [PATCH 5/7] Do a proper cleanup when ptrack.map version is
incompatible
---
engine.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/engine.c b/engine.c
index c8085a0..86a1b60 100644
--- a/engine.c
+++ b/engine.c
@@ -234,8 +234,9 @@ ptrackMapInit(void)
ptrack_map->version_num, ptrack_path, PTRACK_VERSION_NUM),
errdetail("Deleting file \"%s\" and reinitializing ptrack map.", ptrack_path)));
- /* Delete and try again */
- durable_unlink(ptrack_path, LOG);
+ /* Clean up everything and try again */
+ ptrackCleanFilesAndMap();
+
is_new_map = true;
goto ptrack_map_reinit;
}
From ab17447196d46eaf5eef4b2edf07a155a9a8b11a Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Thu, 13 May 2021 20:19:34 +0300
Subject: [PATCH 6/7] Correct some typos
---
engine.c | 6 +++---
ptrack.c | 2 +-
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/engine.c b/engine.c
index 86a1b60..89217a9 100644
--- a/engine.c
+++ b/engine.c
@@ -390,7 +390,7 @@ ptrackCheckpoint(void)
/*
* We are writing ptrack map values to file, but we want to simply map it
* into the memory with mmap after a crash/restart. That way, we have to
- * write values taking into account all paddings/allignments.
+ * write values taking into account all paddings/alignments.
*
* Write both magic and varsion_num at once.
*/
@@ -447,7 +447,7 @@ ptrackCheckpoint(void)
* going to overflow. */
/*
- * We should not have any allignment issues here, since sizeof()
+ * We should not have any alignment issues here, since sizeof()
* takes into account all paddings for us.
*/
ptrack_write_chunk(ptrack_tmp_fd, &crc, (char *) buf, writesz);
@@ -458,7 +458,7 @@ ptrackCheckpoint(void)
}
}
- /* Write if anythig left */
+ /* Write if anything left */
if ((i + 1) % PTRACK_BUF_SIZE != 0)
{
size_t writesz = sizeof(pg_atomic_uint64) * j;
diff --git a/ptrack.c b/ptrack.c
index f2701af..1928499 100644
--- a/ptrack.c
+++ b/ptrack.c
@@ -137,7 +137,7 @@ _PG_fini(void)
/*
* Ptrack follow up for copydir() routine. It parses database OID
- * and tablespace OID from path string. We do not need to recoursively
+ * and tablespace OID from path string. We do not need to recursively
* walk subdirs here, copydir() will do it for us if needed.
*/
static void
From 9c132a3a2f319ed712d11e9158e6dbda27f085b3 Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Fri, 14 May 2021 00:30:15 +0300
Subject: [PATCH 7/7] Refactor stats API and remove ptrack_get_change_file_stat
---
README.md | 1 -
ptrack--2.1--2.2.sql | 41 +++++++++++------------------------------
ptrack.c | 19 +++++++++++++------
t/001_basic.pl | 5 +----
4 files changed, 25 insertions(+), 41 deletions(-)
diff --git a/README.md b/README.md
index 06e4b18..39ea00b 100644
--- a/README.md
+++ b/README.md
@@ -67,7 +67,6 @@ To disable `ptrack` and clean up all remaining service files set `ptrack.map_siz
* ptrack_init_lsn() — returns LSN of the last ptrack map initialization.
* ptrack_get_pagemapset(start_lsn pg_lsn) — returns a set of changed data files with bitmaps of changed blocks since specified `start_lsn`.
* ptrack_get_change_stat(start_lsn pg_lsn) — returns statistic of changes (number of files, pages and size in MB) since specified `start_lsn`.
- * ptrack_get_change_file_stat(start_lsn pg_lsn) — returns per file statistic of changes (number of pages and size in MB) since specified `start_lsn`.
Usage example:
diff --git a/ptrack--2.1--2.2.sql b/ptrack--2.1--2.2.sql
index 2a0d97f..b09c15e 100644
--- a/ptrack--2.1--2.2.sql
+++ b/ptrack--2.1--2.2.sql
@@ -3,10 +3,18 @@
-- Complain if script is sourced in psql, rather than via ALTER EXTENSION
\echo Use "ALTER EXTENSION ptrack UPDATE;" to load this file.\ quit
+DROP FUNCTION ptrack_get_pagemapset(start_lsn pg_lsn);
+CREATE FUNCTION ptrack_get_pagemapset(start_lsn pg_lsn)
+RETURNS TABLE (path text,
+ pagecount bigint,
+ pagemap bytea)
+AS 'MODULE_PATHNAME'
+LANGUAGE C STRICT VOLATILE;
+
CREATE FUNCTION ptrack_get_change_stat(start_lsn pg_lsn)
RETURNS TABLE (
files bigint,
- pages bigint,
+ pages numeric,
"size, MB" numeric
) AS
$func$
@@ -18,37 +26,10 @@ BEGIN
RETURN QUERY
SELECT changed_files,
changed_pages,
- block_size*changed_pages/(1024.0*1024)
+ block_size * changed_pages / (1024.0 * 1024)
FROM
(SELECT count(path) AS changed_files,
- sum(
- length(replace(right((pagemap)::text, -1)::varbit::text, '0', ''))
- ) AS changed_pages
+ sum(pagecount) AS changed_pages
FROM ptrack_get_pagemapset(start_lsn)) s;
END
$func$ LANGUAGE plpgsql;
-
-CREATE FUNCTION ptrack_get_change_file_stat(start_lsn pg_lsn)
- RETURNS TABLE (
- file_path text,
- pages int,
- "size, MB" numeric
- ) AS
-$func$
-DECLARE
-block_size bigint;
-BEGIN
- block_size := (SELECT setting FROM pg_settings WHERE name = 'block_size');
-
- RETURN QUERY
- SELECT s.path,
- changed_pages,
- block_size*changed_pages/(1024.0*1024)
- FROM
- (SELECT path,
- length(replace(right((pagemap)::text, -1)::varbit::text, '0', ''))
- AS changed_pages
- FROM ptrack_get_pagemapset(start_lsn)) s
- ORDER BY (changed_pages, s.path) DESC;
-END
-$func$ LANGUAGE plpgsql;
diff --git a/ptrack.c b/ptrack.c
index 1928499..40630e7 100644
--- a/ptrack.c
+++ b/ptrack.c
@@ -424,6 +424,7 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
FuncCallContext *funcctx;
MemoryContext oldcontext;
datapagemap_t pagemap;
+ int64 pagecount = 0;
char gather_path[MAXPGPATH];
/* Exit immediately if there is no map */
@@ -444,12 +445,13 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
/* Make tuple descriptor */
#if PG_VERSION_NUM >= 120000
- tupdesc = CreateTemplateTupleDesc(2);
+ tupdesc = CreateTemplateTupleDesc(3);
#else
- tupdesc = CreateTemplateTupleDesc(2, false);
+ tupdesc = CreateTemplateTupleDesc(3, false);
#endif
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "path", TEXTOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 2, "pagemap", BYTEAOID, -1, 0);
+ TupleDescInitEntry(tupdesc, (AttrNumber) 2, "pagecount", INT8OID, -1, 0);
+ TupleDescInitEntry(tupdesc, (AttrNumber) 3, "pagemap", BYTEAOID, -1, 0);
funcctx->tuple_desc = BlessTupleDesc(tupdesc);
funcctx->user_fctx = ctx;
@@ -497,8 +499,8 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
/* We completed a segment and there is a bitmap to return */
if (pagemap.bitmap != NULL)
{
- Datum values[2];
- bool nulls[2] = {false};
+ Datum values[3];
+ bool nulls[3] = {false};
char pathname[MAXPGPATH];
bytea *result = NULL;
Size result_sz = pagemap.bitmapsize + VARHDRSZ;
@@ -512,11 +514,13 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
strcpy(pathname, ctx->relpath);
values[0] = CStringGetTextDatum(pathname);
- values[1] = PointerGetDatum(result);
+ values[1] = Int64GetDatum(pagecount);
+ values[2] = PointerGetDatum(result);
pfree(pagemap.bitmap);
pagemap.bitmap = NULL;
pagemap.bitmapsize = 0;
+ pagecount = 0;
htup = heap_form_tuple(funcctx->tuple_desc, values, nulls);
if (htup)
@@ -553,7 +557,10 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
/* Block has been changed since specified LSN. Mark it in the bitmap */
if (update_lsn2 >= ctx->lsn)
+ {
+ pagecount += 1;
datapagemap_add(&pagemap, ctx->bid.blocknum % ((BlockNumber) RELSEG_SIZE));
+ }
}
ctx->bid.blocknum += 1;
diff --git a/t/001_basic.pl b/t/001_basic.pl
index 37285d9..bac81f2 100644
--- a/t/001_basic.pl
+++ b/t/001_basic.pl
@@ -10,7 +10,7 @@
use TestLib;
use Test::More;
-plan tests => 25;
+plan tests => 24;
my $node;
my $res;
@@ -119,9 +119,6 @@
$res_stdout = $node->safe_psql("postgres", "SELECT pages FROM ptrack_get_change_stat('$flush_lsn')");
is($res_stdout > 0, 1, 'should be able to get aggregated stats of changes');
-$res_stdout = $node->safe_psql("postgres", "SELECT count(*) FROM ptrack_get_change_file_stat('$flush_lsn')");
-is($res_stdout > 0, 1, 'should be able to get per file stats of changes');
-
# We should be able to change ptrack map size (but loose all changes)
$node->append_conf(
'postgresql.conf', q{