diff options
| -rw-r--r-- | contrib/pg_walinspect/expected/pg_walinspect.out | 4 | ||||
| -rw-r--r-- | contrib/pg_walinspect/pg_walinspect--1.0--1.1.sql | 23 | ||||
| -rw-r--r-- | contrib/pg_walinspect/pg_walinspect.c | 197 | ||||
| -rw-r--r-- | contrib/pg_walinspect/sql/pg_walinspect.sql | 4 | ||||
| -rw-r--r-- | doc/src/sgml/pgwalinspect.sgml | 205 |
5 files changed, 273 insertions, 160 deletions
diff --git a/contrib/pg_walinspect/expected/pg_walinspect.out b/contrib/pg_walinspect/expected/pg_walinspect.out index b9e2bb994ca..950f0e92175 100644 --- a/contrib/pg_walinspect/expected/pg_walinspect.out +++ b/contrib/pg_walinspect/expected/pg_walinspect.out @@ -121,7 +121,7 @@ UPDATE sample_tbl SET col1 = col1 + 1 WHERE col1 = 1; SELECT pg_current_wal_lsn() AS wal_lsn4 \gset -- Check if we get block data from WAL record. SELECT COUNT(*) >= 1 AS ok FROM pg_get_wal_block_info(:'wal_lsn3', :'wal_lsn4') - WHERE relfilenode = :'sample_tbl_oid' AND blockdata IS NOT NULL; + WHERE relfilenode = :'sample_tbl_oid' AND block_data IS NOT NULL; ok ---- t @@ -134,7 +134,7 @@ UPDATE sample_tbl SET col1 = col1 + 1 WHERE col1 = 2; SELECT pg_current_wal_lsn() AS wal_lsn6 \gset -- Check if we get FPI from WAL record. SELECT COUNT(*) >= 1 AS ok FROM pg_get_wal_block_info(:'wal_lsn5', :'wal_lsn6') - WHERE relfilenode = :'sample_tbl_oid' AND fpi IS NOT NULL; + WHERE relfilenode = :'sample_tbl_oid' AND block_fpi_data IS NOT NULL; ok ---- t diff --git a/contrib/pg_walinspect/pg_walinspect--1.0--1.1.sql b/contrib/pg_walinspect/pg_walinspect--1.0--1.1.sql index 586c3b44677..fdd75e8a729 100644 --- a/contrib/pg_walinspect/pg_walinspect--1.0--1.1.sql +++ b/contrib/pg_walinspect/pg_walinspect--1.0--1.1.sql @@ -12,17 +12,26 @@ DROP FUNCTION pg_get_wal_stats_till_end_of_wal(pg_lsn, boolean); -- CREATE FUNCTION pg_get_wal_block_info(IN start_lsn pg_lsn, IN end_lsn pg_lsn, - OUT lsn pg_lsn, - OUT blockid int2, + OUT start_lsn pg_lsn, + OUT end_lsn pg_lsn, + OUT prev_lsn pg_lsn, + OUT block_id int2, OUT reltablespace oid, OUT reldatabase oid, OUT relfilenode oid, + OUT relforknumber int2, OUT relblocknumber int8, - OUT forkname text, - OUT blockdata bytea, - OUT fpi bytea, - OUT fpilen int4, - OUT fpiinfo text[] + OUT xid xid, + OUT resource_manager text, + OUT record_type text, + OUT record_length int4, + OUT main_data_length int4, + OUT block_data_length int4, + OUT block_fpi_length int4, + OUT block_fpi_info text[], + OUT description text, + OUT block_data bytea, + OUT block_fpi_data bytea ) RETURNS SETOF record AS 'MODULE_PATHNAME', 'pg_get_wal_block_info' diff --git a/contrib/pg_walinspect/pg_walinspect.c b/contrib/pg_walinspect/pg_walinspect.c index 062e90dbce9..1ff53c5abcc 100644 --- a/contrib/pg_walinspect/pg_walinspect.c +++ b/contrib/pg_walinspect/pg_walinspect.c @@ -176,13 +176,18 @@ ReadNextXLogRecord(XLogReaderState *xlogreader) } /* - * Get a single WAL record info. + * Output values that make up a row describing caller's WAL record. + * + * This function leaks memory. Caller may need to use its own custom memory + * context. + * + * Keep this in sync with GetWALBlockInfo. */ static void GetWALRecordInfo(XLogReaderState *record, Datum *values, bool *nulls, uint32 ncols) { - const char *id; + const char *record_type; RmgrData desc; uint32 fpi_len = 0; StringInfoData rec_desc; @@ -190,10 +195,10 @@ GetWALRecordInfo(XLogReaderState *record, Datum *values, int i = 0; desc = GetRmgr(XLogRecGetRmid(record)); - id = desc.rm_identify(XLogRecGetInfo(record)); + record_type = desc.rm_identify(XLogRecGetInfo(record)); - if (id == NULL) - id = psprintf("UNKNOWN (%x)", XLogRecGetInfo(record) & ~XLR_INFO_MASK); + if (record_type == NULL) + record_type = psprintf("UNKNOWN (%x)", XLogRecGetInfo(record) & ~XLR_INFO_MASK); initStringInfo(&rec_desc); desc.rm_desc(&rec_desc, record); @@ -209,7 +214,7 @@ GetWALRecordInfo(XLogReaderState *record, Datum *values, values[i++] = LSNGetDatum(XLogRecGetPrev(record)); values[i++] = TransactionIdGetDatum(XLogRecGetXid(record)); values[i++] = CStringGetTextDatum(desc.rm_name); - values[i++] = CStringGetTextDatum(id); + values[i++] = CStringGetTextDatum(record_type); values[i++] = UInt32GetDatum(XLogRecGetTotalLen(record)); values[i++] = UInt32GetDatum(XLogRecGetDataLen(record)); values[i++] = UInt32GetDatum(fpi_len); @@ -229,24 +234,48 @@ GetWALRecordInfo(XLogReaderState *record, Datum *values, /* - * Store a set of block information from a single record (FPI and block - * information). + * Output one or more rows in rsinfo tuple store, each describing a single + * block reference from caller's WAL record. (Should only be called with + * records that have block references.) + * + * This function leaks memory. Caller may need to use its own custom memory + * context. + * + * Keep this in sync with GetWALRecordInfo. */ static void GetWALBlockInfo(FunctionCallInfo fcinfo, XLogReaderState *record) { -#define PG_GET_WAL_BLOCK_INFO_COLS 11 +#define PG_GET_WAL_BLOCK_INFO_COLS 20 int block_id; ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo; + RmgrData desc; + const char *record_type; + StringInfoData rec_desc; + + Assert(XLogRecHasAnyBlockRefs(record)); + + desc = GetRmgr(XLogRecGetRmid(record)); + record_type = desc.rm_identify(XLogRecGetInfo(record)); + + if (record_type == NULL) + record_type = psprintf("UNKNOWN (%x)", + XLogRecGetInfo(record) & ~XLR_INFO_MASK); + + initStringInfo(&rec_desc); + desc.rm_desc(&rec_desc, record); for (block_id = 0; block_id <= XLogRecMaxBlockId(record); block_id++) { DecodedBkpBlock *blk; BlockNumber blkno; RelFileLocator rnode; - ForkNumber fork; + ForkNumber forknum; Datum values[PG_GET_WAL_BLOCK_INFO_COLS] = {0}; bool nulls[PG_GET_WAL_BLOCK_INFO_COLS] = {0}; + uint32 block_data_len = 0, + block_fpi_len = 0; + ArrayType *block_fpi_info = NULL; int i = 0; if (!XLogRecHasBlockRef(record, block_id)) @@ -255,99 +284,117 @@ GetWALBlockInfo(FunctionCallInfo fcinfo, XLogReaderState *record) blk = XLogRecGetBlock(record, block_id); (void) XLogRecGetBlockTagExtended(record, block_id, - &rnode, &fork, &blkno, NULL); + &rnode, &forknum, &blkno, NULL); + /* Save block_data_len */ + if (blk->has_data) + block_data_len = blk->data_len; + + if (blk->has_image) + { + /* Block reference has an FPI, so prepare relevant output */ + int bitcnt; + int cnt = 0; + Datum *flags; + + /* Save block_fpi_len */ + block_fpi_len = blk->bimg_len; + + /* Construct and save block_fpi_info */ + bitcnt = pg_popcount((const char *) &blk->bimg_info, + sizeof(uint8)); + flags = (Datum *) palloc0(sizeof(Datum) * bitcnt); + if ((blk->bimg_info & BKPIMAGE_HAS_HOLE) != 0) + flags[cnt++] = CStringGetTextDatum("HAS_HOLE"); + if (blk->apply_image) + flags[cnt++] = CStringGetTextDatum("APPLY"); + if ((blk->bimg_info & BKPIMAGE_COMPRESS_PGLZ) != 0) + flags[cnt++] = CStringGetTextDatum("COMPRESS_PGLZ"); + if ((blk->bimg_info & BKPIMAGE_COMPRESS_LZ4) != 0) + flags[cnt++] = CStringGetTextDatum("COMPRESS_LZ4"); + if ((blk->bimg_info & BKPIMAGE_COMPRESS_ZSTD) != 0) + flags[cnt++] = CStringGetTextDatum("COMPRESS_ZSTD"); + + Assert(cnt <= bitcnt); + block_fpi_info = construct_array_builtin(flags, cnt, TEXTOID); + } + + /* start_lsn, end_lsn, prev_lsn, and blockid outputs */ values[i++] = LSNGetDatum(record->ReadRecPtr); + values[i++] = LSNGetDatum(record->EndRecPtr); + values[i++] = LSNGetDatum(XLogRecGetPrev(record)); values[i++] = Int16GetDatum(block_id); + + /* relfile and block related outputs */ values[i++] = ObjectIdGetDatum(blk->rlocator.spcOid); values[i++] = ObjectIdGetDatum(blk->rlocator.dbOid); values[i++] = ObjectIdGetDatum(blk->rlocator.relNumber); + values[i++] = Int16GetDatum(forknum); values[i++] = Int64GetDatum((int64) blkno); - if (fork >= 0 && fork <= MAX_FORKNUM) - values[i++] = CStringGetTextDatum(forkNames[fork]); + /* xid, resource_manager, and record_type outputs */ + values[i++] = TransactionIdGetDatum(XLogRecGetXid(record)); + values[i++] = CStringGetTextDatum(desc.rm_name); + values[i++] = CStringGetTextDatum(record_type); + + /* + * record_length, main_data_length, block_data_len, and + * block_fpi_length outputs + */ + values[i++] = UInt32GetDatum(XLogRecGetTotalLen(record)); + values[i++] = UInt32GetDatum(XLogRecGetDataLen(record)); + values[i++] = UInt32GetDatum(block_data_len); + values[i++] = UInt32GetDatum(block_fpi_len); + + /* block_fpi_info (text array) output */ + if (block_fpi_info) + values[i++] = PointerGetDatum(block_fpi_info); else - ereport(ERROR, - (errcode(ERRCODE_INTERNAL_ERROR), - errmsg_internal("invalid fork number: %u", fork))); + nulls[i++] = true; - /* Block data */ + /* description output (describes WAL record) */ + if (rec_desc.len > 0) + values[i++] = CStringGetTextDatum(rec_desc.data); + else + nulls[i++] = true; + + /* block_data output */ if (blk->has_data) { - bytea *raw_data; + bytea *block_data; - /* Initialize bytea buffer to copy the data to */ - raw_data = (bytea *) palloc(blk->data_len + VARHDRSZ); - SET_VARSIZE(raw_data, blk->data_len + VARHDRSZ); - - /* Copy the data */ - memcpy(VARDATA(raw_data), blk->data, blk->data_len); - values[i++] = PointerGetDatum(raw_data); + block_data = (bytea *) palloc(block_data_len + VARHDRSZ); + SET_VARSIZE(block_data, block_data_len + VARHDRSZ); + memcpy(VARDATA(block_data), blk->data, block_data_len); + values[i++] = PointerGetDatum(block_data); } else - { - /* No data, so set this field to NULL */ nulls[i++] = true; - } + /* block_fpi_data output */ if (blk->has_image) { PGAlignedBlock buf; Page page; - bytea *raw_page; - int bitcnt; - int cnt = 0; - Datum *flags; - ArrayType *a; + bytea *block_fpi_data; page = (Page) buf.data; - - /* Full page image exists, so let's save it */ if (!RestoreBlockImage(record, block_id, page)) ereport(ERROR, (errcode(ERRCODE_INTERNAL_ERROR), errmsg_internal("%s", record->errormsg_buf))); - /* Initialize bytea buffer to copy the FPI to */ - raw_page = (bytea *) palloc(BLCKSZ + VARHDRSZ); - SET_VARSIZE(raw_page, BLCKSZ + VARHDRSZ); - - /* Take a verbatim copy of the FPI */ - memcpy(VARDATA(raw_page), page, BLCKSZ); - - values[i++] = PointerGetDatum(raw_page); - values[i++] = UInt32GetDatum(blk->bimg_len); - - /* FPI flags */ - bitcnt = pg_popcount((const char *) &blk->bimg_info, - sizeof(uint8)); - /* Build set of raw flags */ - flags = (Datum *) palloc0(sizeof(Datum) * bitcnt); - - if ((blk->bimg_info & BKPIMAGE_HAS_HOLE) != 0) - flags[cnt++] = CStringGetTextDatum("HAS_HOLE"); - if (blk->apply_image) - flags[cnt++] = CStringGetTextDatum("APPLY"); - if ((blk->bimg_info & BKPIMAGE_COMPRESS_PGLZ) != 0) - flags[cnt++] = CStringGetTextDatum("COMPRESS_PGLZ"); - if ((blk->bimg_info & BKPIMAGE_COMPRESS_LZ4) != 0) - flags[cnt++] = CStringGetTextDatum("COMPRESS_LZ4"); - if ((blk->bimg_info & BKPIMAGE_COMPRESS_ZSTD) != 0) - flags[cnt++] = CStringGetTextDatum("COMPRESS_ZSTD"); - - Assert(cnt <= bitcnt); - a = construct_array_builtin(flags, cnt, TEXTOID); - values[i++] = PointerGetDatum(a); + block_fpi_data = (bytea *) palloc(BLCKSZ + VARHDRSZ); + SET_VARSIZE(block_fpi_data, BLCKSZ + VARHDRSZ); + memcpy(VARDATA(block_fpi_data), page, BLCKSZ); + values[i++] = PointerGetDatum(block_fpi_data); } else - { - /* No full page image, so store NULLs for all its fields */ - memset(&nulls[i], true, 3 * sizeof(bool)); - i += 3; - } + nulls[i++] = true; Assert(i == PG_GET_WAL_BLOCK_INFO_COLS); + /* Store a tuple for this block reference */ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls); } @@ -356,11 +403,7 @@ GetWALBlockInfo(FunctionCallInfo fcinfo, XLogReaderState *record) } /* - * Get information about all the blocks saved in WAL records between start - * and end LSNs. This produces information about the full page images with - * their relation information, and the data saved in each block associated - * to a record. Decompression is applied to the full page images, if - * necessary. + * Get WAL record info, unnested by block reference */ Datum pg_get_wal_block_info(PG_FUNCTION_ARGS) @@ -484,7 +527,7 @@ ValidateInputLSNs(XLogRecPtr start_lsn, XLogRecPtr *end_lsn) } /* - * Get info and data of all WAL records between start LSN and end LSN. + * Get info of all WAL records between start LSN and end LSN. */ static void GetWALRecordsInfo(FunctionCallInfo fcinfo, XLogRecPtr start_lsn, @@ -536,7 +579,7 @@ GetWALRecordsInfo(FunctionCallInfo fcinfo, XLogRecPtr start_lsn, } /* - * Get info and data of all WAL records between start LSN and end LSN. + * Get info of all WAL records between start LSN and end LSN. */ Datum pg_get_wal_records_info(PG_FUNCTION_ARGS) diff --git a/contrib/pg_walinspect/sql/pg_walinspect.sql b/contrib/pg_walinspect/sql/pg_walinspect.sql index 2f0a909c183..0541e5fbf1f 100644 --- a/contrib/pg_walinspect/sql/pg_walinspect.sql +++ b/contrib/pg_walinspect/sql/pg_walinspect.sql @@ -78,7 +78,7 @@ UPDATE sample_tbl SET col1 = col1 + 1 WHERE col1 = 1; SELECT pg_current_wal_lsn() AS wal_lsn4 \gset -- Check if we get block data from WAL record. SELECT COUNT(*) >= 1 AS ok FROM pg_get_wal_block_info(:'wal_lsn3', :'wal_lsn4') - WHERE relfilenode = :'sample_tbl_oid' AND blockdata IS NOT NULL; + WHERE relfilenode = :'sample_tbl_oid' AND block_data IS NOT NULL; -- Force full-page image on the next update. SELECT pg_current_wal_lsn() AS wal_lsn5 \gset @@ -87,7 +87,7 @@ UPDATE sample_tbl SET col1 = col1 + 1 WHERE col1 = 2; SELECT pg_current_wal_lsn() AS wal_lsn6 \gset -- Check if we get FPI from WAL record. SELECT COUNT(*) >= 1 AS ok FROM pg_get_wal_block_info(:'wal_lsn5', :'wal_lsn6') - WHERE relfilenode = :'sample_tbl_oid' AND fpi IS NOT NULL; + WHERE relfilenode = :'sample_tbl_oid' AND block_fpi_data IS NOT NULL; -- =================================================================== -- Tests for permissions diff --git a/doc/src/sgml/pgwalinspect.sgml b/doc/src/sgml/pgwalinspect.sgml index 9a0241a8d67..300ffac3744 100644 --- a/doc/src/sgml/pgwalinspect.sgml +++ b/doc/src/sgml/pgwalinspect.sgml @@ -18,29 +18,38 @@ <para> All the functions of this module will provide the WAL information using the - current server's timeline ID. - </para> - - <para> - All the functions of this module will try to find the first valid WAL record - that is at or after the given <replaceable>in_lsn</replaceable> or - <replaceable>start_lsn</replaceable> and will emit error if no such record - is available. Similarly, the <replaceable>end_lsn</replaceable> must be - available, and if it falls in the middle of a record, the entire record must - be available. + server's current timeline ID. </para> <note> <para> - Some functions, such as <function><link - linkend="pg-logical-emit-message">pg_logical_emit_message</link></function>, - return the LSN <emphasis>after</emphasis> the record just - inserted. Therefore, if you pass that LSN as - <replaceable>in_lsn</replaceable> or <replaceable>start_lsn</replaceable> - to one of these functions, it will return the <emphasis>next</emphasis> - record. + The <filename>pg_walinspect</filename> functions are often called + using an LSN argument that specifies the location at which a known + WAL record of interest <emphasis>begins</emphasis>. However, some + functions, such as + <function><link linkend="pg-logical-emit-message">pg_logical_emit_message</link></function>, + return the LSN <emphasis>after</emphasis> the record that was just + inserted. </para> </note> + <tip> + <para> + All of the <filename>pg_walinspect</filename> functions that show + information about records that fall within a certain LSN range are + permissive about accepting <replaceable>end_lsn</replaceable> + arguments that are after the server's current LSN. Using an + <replaceable>end_lsn</replaceable> <quote>from the future</quote> + will not raise an error. + </para> + <para> + It may be convenient to provide the value + <literal>FFFFFFFF/FFFFFFFF</literal> (the maximum valid + <type>pg_lsn</type> value) as an <replaceable>end_lsn</replaceable> + argument. This is equivalent to providing an + <replaceable>end_lsn</replaceable> argument matching the server's + current LSN. + </para> + </tip> <para> By default, use of these functions is restricted to superusers and members of the <literal>pg_read_server_files</literal> role. Access may be granted by @@ -58,11 +67,9 @@ <listitem> <para> - Gets WAL record information of a given LSN. If the given LSN isn't - at the start of a WAL record, it gives the information of the next - available valid WAL record; or an error if no such record is found. - For example, usage of the function is as - follows: + Gets WAL record information about a record that is located at or + after the <replaceable>in_lsn</replaceable> argument. For + example: <screen> postgres=# SELECT * FROM pg_get_wal_record_info('0/1E826E98'); -[ RECORD 1 ]----+---------------------------------------------------- @@ -79,6 +86,12 @@ description | snapshotConflictHorizon 33748 nredirected 0 ndead 2 block_ref | blkref #0: rel 1663/5/60221 fork main blk 2 </screen> </para> + <para> + If <replaceable>in_lsn</replaceable> isn't at the start of a WAL + record, information about the next valid WAL record is shown + instead. If there is no next valid WAL record, the function + raises an error. + </para> </listitem> </varlistentry> @@ -94,11 +107,7 @@ block_ref | blkref #0: rel 1663/5/60221 fork main blk 2 <para> Gets information of all the valid WAL records between <replaceable>start_lsn</replaceable> and <replaceable>end_lsn</replaceable>. - Returns one row per WAL record. If a future - <replaceable>end_lsn</replaceable> (i.e. ahead of the current LSN of - the server) is specified, it returns information until the end of WAL. - The function raises an error if <replaceable>start_lsn</replaceable> - is not available. For example, usage of the function is as follows: + Returns one row per WAL record. For example: <screen> postgres=# SELECT * FROM pg_get_wal_records_info('0/1E913618', '0/1E913740') LIMIT 1; -[ RECORD 1 ]----+-------------------------------------------------------------- @@ -115,6 +124,99 @@ description | nextXid 33775 latestCompletedXid 33774 oldestRunningXid 33775 block_ref | </screen> </para> + <para> + The function raises an error if + <replaceable>start_lsn</replaceable> is not available. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term> + <function>pg_get_wal_block_info(start_lsn pg_lsn, end_lsn pg_lsn) returns setof record</function> + </term> + + <listitem> + <para> + Gets information about each block reference from all the valid + WAL records between <replaceable>start_lsn</replaceable> and + <replaceable>end_lsn</replaceable> with one or more block + references. Returns one row per block reference per WAL record. + For example: +<screen> +postgres=# SELECT * FROM pg_get_wal_block_info('0/10E9D80', '0/10E9DC0') LIMIT 1; +-[ RECORD 1 ]-----+----------------------------------- +start_lsn | 0/10E9D80 +end_lsn | 0/10E9DC0 +prev_lsn | 0/10E9860 +block_id | 0 +reltablespace | 1663 +reldatabase | 1 +relfilenode | 2690 +relforknumber | 0 +relblocknumber | 5 +xid | 117 +resource_manager | Btree +record_type | INSERT_LEAF +record_length | 64 +main_data_length | 2 +block_data_length | 16 +block_fpi_length | 0 +block_fpi_info | +description | off 14 +block_data | \x00005400020010001407000000000000 +block_fpi_data | +</screen> + </para> + <para> + This example involves a WAL record that only contains one block + reference, but many WAL records contain several block + references. Rows output by + <function>pg_get_wal_block_info</function> are guaranteed to + have a unique combination of + <replaceable>start_lsn</replaceable> and + <replaceable>block_id</replaceable> values. + </para> + <para> + Much of the information shown here matches the output that + <function>pg_get_wal_records_info</function> would show, given + the same arguments. However, + <function>pg_get_wal_block_info</function> unnests the + information from each WAL record into an expanded form by + outputting one row per block reference, so certain details are + tracked at the block reference level rather than at the + whole-record level. This structure is useful with queries that + track how individual blocks changed over time. Note that + records with no block references (e.g., + <literal>COMMIT</literal> WAL records) will have no rows + returned, so <function>pg_get_wal_block_info</function> may + actually return <emphasis>fewer</emphasis> rows than + <function>pg_get_wal_records_info</function>. + </para> + <para> + The <structfield>reltablespace</structfield>, + <structfield>reldatabase</structfield>, and + <structfield>relfilenode</structfield> parameters reference + <link linkend="catalog-pg-tablespace"><structname>pg_tablespace</structname></link>.<structfield>oid</structfield>, + <link linkend="catalog-pg-database"><structname>pg_database</structname></link>.<structfield>oid</structfield>, and + <link linkend="catalog-pg-class"><structname>pg_class</structname></link>.<structfield>relfilenode</structfield> + respectively. The <structfield>relforknumber</structfield> + field is the fork number within the relation for the block + reference; see <filename>common/relpath.h</filename> for + details. + </para> + <tip> + <para> + The <function>pg_filenode_relation</function> function (see + <xref linkend="functions-admin-dblocation"/>) can help you to + determine which block/relation was modified by each WAL record + during original execution + </para> + </tip> + <para> + The function raises an error if + <replaceable>start_lsn</replaceable> is not available. + </para> </listitem> </varlistentry> @@ -133,11 +235,8 @@ block_ref | <replaceable>end_lsn</replaceable>. By default, it returns one row per <replaceable>resource_manager</replaceable> type. When <replaceable>per_record</replaceable> is set to <literal>true</literal>, - it returns one row per <replaceable>record_type</replaceable>. If a - future <replaceable>end_lsn</replaceable> (i.e. ahead of the current - LSN of the server) is specified, it returns statistics until the end - of WAL. An error is raised if <replaceable>start_lsn</replaceable> is - not available. For example, usage of the function is as follows: + it returns one row per <replaceable>record_type</replaceable>. + For example: <screen> postgres=# SELECT * FROM pg_get_wal_stats('0/1E847D00', '0/1E84F500') WHERE count > 0 LIMIT 1 AND @@ -154,47 +253,9 @@ combined_size | 875 combined_size_percentage | 2.8634072910530795 </screen> </para> - </listitem> - </varlistentry> - - <varlistentry> - <term> - <function>pg_get_wal_block_info(start_lsn pg_lsn, end_lsn pg_lsn) returns setof record</function> - </term> - - <listitem> <para> - Gets a copy of the block information stored in WAL records. This includes - copies of the block data (<literal>NULL</literal> if none) and full page - images as <type>bytea</type> values (after - applying decompression when necessary, or <literal>NULL</literal> if none) - and their information associated with all the valid WAL records between - <replaceable>start_lsn</replaceable> and - <replaceable>end_lsn</replaceable>. Returns one row per block registered - in a WAL record. If a future <replaceable>end_lsn</replaceable> (i.e. - ahead of the current LSN of the server) is specified, it returns - statistics until the end of WAL. An error is raised if - <replaceable>start_lsn</replaceable> is not available. For example, - usage of the function is as follows: -<screen> -postgres=# SELECT lsn, blockid, reltablespace, reldatabase, relfilenode, - relblocknumber, forkname, - substring(blockdata for 24) as block_trimmed, - substring(fpi for 24) as fpi_trimmed, fpilen, fpiinfo - FROM pg_get_wal_block_info('0/1871080', '0/1871440'); --[ RECORD 1 ]--+--------------------------------------------------- -lsn | 0/18712F8 -blockid | 0 -reltablespace | 1663 -reldatabase | 16384 -relfilenode | 16392 -relblocknumber | 0 -forkname | main -block_trimmed | \x02800128180164000000 -fpi_trimmed | \x0000000050108701000000002c00601f00200420e0020000 -fpilen | 204 -fpiinfo | {HAS_HOLE,APPLY} -</screen> + The function raises an error if + <replaceable>start_lsn</replaceable> is not available. </para> </listitem> </varlistentry> |