--- /dev/null
+<!--
+doc/src/sgml/ref/pg_walsummary.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="app-pgwalsummary">
+ <indexterm zone="app-pgwalsummary">
+ <primary>pg_walsummary</primary>
+ </indexterm>
+
+ <refmeta>
+ <refentrytitle><application>pg_walsummary</application></refentrytitle>
+ <manvolnum>1</manvolnum>
+ <refmiscinfo>Application</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+ <refname>pg_walsummary</refname>
+ <refpurpose>print contents of WAL summary files</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <cmdsynopsis>
+ <command>pg_walsummary</command>
+ <arg rep="repeat" choice="opt"><replaceable>option</replaceable></arg>
+ <arg rep="repeat"><replaceable>file</replaceable></arg>
+ </cmdsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+ <para>
+ <application>pg_walsummary</application> is used to print the contents of
+ WAL summary files. These binary files are found with the
+ <literal>pg_wal/summaries</literal> subdirectory of the data directory,
+ and can be converted to text using this tool. This is not ordinarily
+ necessary, since WAL summary files primarily exist to support
+ <link linkend="backup-incremental-backup">incremental backup</link>,
+ but it may be useful for debugging purposes.
+ </para>
+
+ <para>
+ A WAL summary file is indexed by tablespace OID, relation OID, and relation
+ fork. For each relation fork, it stores the list of blocks that were
+ modified by WAL within the range summarized in the file. It can also
+ store a "limit block," which is 0 if the relation fork was created or
+ truncated within the relevant WAL range, and otherwise the shortest length
+ to which the relation fork was truncated. If the relation fork was not
+ created, deleted, or truncated within the relevant WAL range, the limit
+ block is undefined or infinite and will not be printed by this tool.
+ </para>
+ </refsect1>
+
+ <refsect1>
+ <title>Options</title>
+
+ <para>
+ <variablelist>
+ <varlistentry>
+ <term><option>-i</option></term>
+ <term><option>--indivudual</option></term>
+ <listitem>
+ <para>
+ By default, <literal>pg_walsummary</literal> prints one line of output
+ for each range of one or more consecutive modified blocks. This can
+ make the output a lot briefer, since a relation where all blocks from
+ 0 through 999 were modified will produce only one line of output rather
+ than 1000 separate lines. This option requests a separate line of
+ output for every modified block.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-q</option></term>
+ <term><option>--quiet</option></term>
+ <listitem>
+ <para>
+ Do not print any output, except for errors. This can be useful
+ when you want to know whether a WAL summary file can be successfully
+ parsed but don't care about the contents.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-?</option></term>
+ <term><option>--help</option></term>
+ <listitem>
+ <para>
+ Shows help about <application>pg_walsummary</application> command line
+ arguments, and exits.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ </variablelist>
+ </para>
+
+ </refsect1>
+
+ <refsect1>
+ <title>Environment</title>
+
+ <para>
+ The environment variable <envar>PG_COLOR</envar> specifies whether to use
+ color in diagnostic messages. Possible values are
+ <literal>always</literal>, <literal>auto</literal> and
+ <literal>never</literal>.
+ </para>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+
+ <simplelist type="inline">
+ <member><xref linkend="app-pgbasebackup"/></member>
+ <member><xref linkend="app-pgcombinebackup"/></member>
+ </simplelist>
+ </refsect1>
+
+</refentry>
--- /dev/null
+/*-------------------------------------------------------------------------
+ *
+ * pg_walsummary.c
+ * Prints the contents of WAL summary files.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ * src/bin/pg_walsummary/pg_walsummary.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres_fe.h"
+
+#include <fcntl.h>
+#include <limits.h>
+
+#include "common/blkreftable.h"
+#include "common/logging.h"
+#include "fe_utils/option_utils.h"
+#include "lib/stringinfo.h"
+#include "getopt_long.h"
+
+typedef struct ws_options
+{
+ bool individual;
+ bool quiet;
+} ws_options;
+
+typedef struct ws_file_info
+{
+ int fd;
+ char *filename;
+} ws_file_info;
+
+static BlockNumber *block_buffer = NULL;
+static unsigned block_buffer_size = 512; /* Initial size. */
+
+static void dump_one_relation(ws_options *opt, RelFileLocator *rlocator,
+ ForkNumber forknum, BlockNumber limit_block,
+ BlockRefTableReader *reader);
+static void help(const char *progname);
+static int compare_block_numbers(const void *a, const void *b);
+static int walsummary_read_callback(void *callback_arg, void *data,
+ int length);
+static void walsummary_error_callback(void *callback_arg, char *fmt,...) pg_attribute_printf(2, 3);
+
+/*
+ * Main program.
+ */
+int
+main(int argc, char *argv[])
+{
+ static struct option long_options[] = {
+ {"individual", no_argument, NULL, 'i'},
+ {"quiet", no_argument, NULL, 'q'},
+ {NULL, 0, NULL, 0}
+ };
+
+ const char *progname;
+ int optindex;
+ int c;
+ ws_options opt;
+
+ memset(&opt, 0, sizeof(ws_options));
+
+ pg_logging_init(argv[0]);
+ progname = get_progname(argv[0]);
+ handle_help_version_opts(argc, argv, progname, help);
+
+ /* process command-line options */
+ while ((c = getopt_long(argc, argv, "f:iqw:",
+ long_options, &optindex)) != -1)
+ {
+ switch (c)
+ {
+ case 'i':
+ opt.individual = true;
+ break;
+ case 'q':
+ opt.quiet = true;
+ break;
+ default:
+ /* getopt_long already emitted a complaint */
+ pg_log_error_hint("Try \"%s --help\" for more information.", progname);
+ exit(1);
+ }
+ }
+
+ if (optind >= argc)
+ {
+ pg_log_error("%s: no input files specified", progname);
+ pg_log_error_hint("Try \"%s --help\" for more information.", progname);
+ exit(1);
+ }
+
+ while (optind < argc)
+ {
+ ws_file_info ws;
+ BlockRefTableReader *reader;
+ RelFileLocator rlocator;
+ ForkNumber forknum;
+ BlockNumber limit_block;
+
+ ws.filename = argv[optind++];
+ if ((ws.fd = open(ws.filename, O_RDONLY | PG_BINARY, 0)) < 0)
+ pg_fatal("could not open file \"%s\": %m", ws.filename);
+
+ reader = CreateBlockRefTableReader(walsummary_read_callback, &ws,
+ ws.filename,
+ walsummary_error_callback, NULL);
+ while (BlockRefTableReaderNextRelation(reader, &rlocator, &forknum,
+ &limit_block))
+ dump_one_relation(&opt, &rlocator, forknum, limit_block, reader);
+
+ DestroyBlockRefTableReader(reader);
+ close(ws.fd);
+ }
+
+ exit(0);
+}
+
+/*
+ * Dump details for one relation.
+ */
+static void
+dump_one_relation(ws_options *opt, RelFileLocator *rlocator,
+ ForkNumber forknum, BlockNumber limit_block,
+ BlockRefTableReader *reader)
+{
+ unsigned i = 0;
+ unsigned nblocks;
+ BlockNumber startblock = InvalidBlockNumber;
+ BlockNumber endblock = InvalidBlockNumber;
+
+ /* Dump limit block, if any. */
+ if (limit_block != InvalidBlockNumber)
+ printf("TS %u, DB %u, REL %u, FORK %s: limit %u\n",
+ rlocator->spcOid, rlocator->dbOid, rlocator->relNumber,
+ forkNames[forknum], limit_block);
+
+ /* If we haven't allocated a block buffer yet, do that now. */
+ if (block_buffer == NULL)
+ block_buffer = palloc_array(BlockNumber, block_buffer_size);
+
+ /* Try to fill the block buffer. */
+ nblocks = BlockRefTableReaderGetBlocks(reader,
+ block_buffer,
+ block_buffer_size);
+
+ /* If we filled the block buffer completely, we must enlarge it. */
+ while (nblocks >= block_buffer_size)
+ {
+ unsigned new_size;
+
+ /* Double the size, being careful about overflow. */
+ new_size = block_buffer_size * 2;
+ if (new_size < block_buffer_size)
+ new_size = PG_UINT32_MAX;
+ block_buffer = repalloc_array(block_buffer, BlockNumber, new_size);
+
+ /* Try to fill the newly-allocated space. */
+ nblocks +=
+ BlockRefTableReaderGetBlocks(reader,
+ block_buffer + block_buffer_size,
+ new_size - block_buffer_size);
+
+ /* Save the new size for later calls. */
+ block_buffer_size = new_size;
+ }
+
+ /* If we don't need to produce any output, skip the rest of this. */
+ if (opt->quiet)
+ return;
+
+ /*
+ * Sort the returned block numbers. If the block reference table was using
+ * the bitmap representation for a given chunk, the block numbers in that
+ * chunk will already be sorted, but when the array-of-offsets
+ * representation is used, we can receive block numbers here out of order.
+ */
+ qsort(block_buffer, nblocks, sizeof(BlockNumber), compare_block_numbers);
+
+ /* Dump block references. */
+ while (i < nblocks)
+ {
+ /*
+ * Find the next range of blocks to print, but if --individual was
+ * specified, then consider each block a separate range.
+ */
+ startblock = endblock = block_buffer[i++];
+ if (!opt->individual)
+ {
+ while (i < nblocks && block_buffer[i] == endblock + 1)
+ {
+ endblock++;
+ i++;
+ }
+ }
+
+ /* Format this range of block numbers as a string. */
+ if (startblock == endblock)
+ printf("TS %u, DB %u, REL %u, FORK %s: block %u\n",
+ rlocator->spcOid, rlocator->dbOid, rlocator->relNumber,
+ forkNames[forknum], startblock);
+ else
+ printf("TS %u, DB %u, REL %u, FORK %s: blocks %u..%u\n",
+ rlocator->spcOid, rlocator->dbOid, rlocator->relNumber,
+ forkNames[forknum], startblock, endblock);
+ }
+}
+
+/*
+ * Quicksort comparator for block numbers.
+ */
+static int
+compare_block_numbers(const void *a, const void *b)
+{
+ BlockNumber aa = *(BlockNumber *) a;
+ BlockNumber bb = *(BlockNumber *) b;
+
+ if (aa > bb)
+ return 1;
+ else if (aa == bb)
+ return 0;
+ else
+ return -1;
+}
+
+/*
+ * Error callback.
+ */
+void
+walsummary_error_callback(void *callback_arg, char *fmt,...)
+{
+ va_list ap;
+
+ va_start(ap, fmt);
+ pg_log_generic_v(PG_LOG_ERROR, PG_LOG_PRIMARY, fmt, ap);
+ va_end(ap);
+
+ exit(1);
+}
+
+/*
+ * Read callback.
+ */
+int
+walsummary_read_callback(void *callback_arg, void *data, int length)
+{
+ ws_file_info *ws = callback_arg;
+ int rc;
+
+ if ((rc = read(ws->fd, data, length)) < 0)
+ pg_fatal("could not read file \"%s\": %m", ws->filename);
+
+ return rc;
+}
+
+/*
+ * help
+ *
+ * Prints help page for the program
+ *
+ * progname: the name of the executed program, such as "pg_walsummary"
+ */
+static void
+help(const char *progname)
+{
+ printf(_("%s prints the contents of a WAL summary file.\n\n"), progname);
+ printf(_("Usage:\n"));
+ printf(_(" %s [OPTION]... FILE...\n"), progname);
+ printf(_("\nOptions:\n"));
+ printf(_(" -i, --individual list block numbers individually, not as ranges\n"));
+ printf(_(" -q, --quiet don't print anything, just parse the files\n"));
+ printf(_(" -?, --help show this help, then exit\n"));
+
+ printf(_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
+ printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
+}
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