Update pg_resetxlog's documentation on multixacts

I added some more functionality to it in 0ac5ad5134f27 but neglected to
add it to the docs.

Per Peter Eisentraut in message
1367112171[email protected]

diff --git a/doc/src/sgml/ref/pg_resetxlog.sgml b/doc/src/sgml/ref/pg_resetxlog.sgml
index 90c772195cd2c1d3ac593b18efa27c89d7c804b5..c680680fe781c19fb3a319ae26b1ec20f50635a4 100644 (file)
--- a/doc/src/sgml/ref/pg_resetxlog.sgml
+++ b/doc/src/sgml/ref/pg_resetxlog.sgml
@@ -27,7 +27,7 @@ PostgreSQL documentation
    -o oid
    -x xid
    -e xid_epoch
-   -m mxid
+   -m mxid,mxid
    -O mxoff
    -l xlogfile
    datadir
@@ -81,7 +81,7 @@ PostgreSQL documentation
    -m, -O,
    and -l
    options allow the next OID, next transaction ID, next transaction ID's
-   epoch, next multitransaction ID, next multitransaction offset, and WAL
+   epoch, next and oldest multitransaction ID, next multitransaction offset, and WAL
    starting address values to be set manually.  These are only needed when
    pg_resetxlog is unable to determine appropriate values
    by reading pg_control.  Safe values can be determined as
@@ -104,12 +104,16 @@ PostgreSQL documentation
 
     
      
-      A safe value for the next multitransaction ID (-m)
+      A safe value for the next multitransaction ID (first part of -m)
       can be determined by looking for the numerically largest
       file name in the directory pg_multixact/offsets under the
-      data directory, adding one, and then multiplying by 65536.  As above,
-      the file names are in hexadecimal, so the easiest way to do this is to
-      specify the option value in hexadecimal and add four zeroes.
+      data directory, adding one, and then multiplying by 65536.
+      Conversely, a safe value for the oldest multitransaction ID (second part of
+      -m)
+      can be determined by looking for the numerically smallest
+      file name in the same directory and multiplying by 65536.
+      As above, the file names are in hexadecimal, so the easiest way to do
+      this is to specify the option value in hexadecimal and append four zeroes.
      
     
 
@@ -118,9 +122,9 @@ PostgreSQL documentation
       A safe value for the next multitransaction offset (-O)
       can be determined by looking for the numerically largest
       file name in the directory pg_multixact/members under the
-      data directory, adding one, and then multiplying by 65536.  As above,
-      the file names are in hexadecimal, so the easiest way to do this is to
-      specify the option value in hexadecimal and add four zeroes.
+      data directory, adding one, and then multiplying by 52352.  As above,
+      the file names are in hexadecimal.  There is no simple recipe such as
+      the ones above of appending zeroes.
      
     
 

diff --git a/src/bin/pg_resetxlog/pg_resetxlog.c b/src/bin/pg_resetxlog/pg_resetxlog.c
index 82018e449f27218f57be22e78568d04f4bf9ad2b..6d3e9f5439f652f1ddac73c0c5b4d86bc7d571c7 100644 (file)
--- a/src/bin/pg_resetxlog/pg_resetxlog.c
+++ b/src/bin/pg_resetxlog/pg_resetxlog.c
@@ -1036,7 +1036,7 @@ usage(void)
    printf(_("  -e XIDEPOCH      set next transaction ID epoch\n"));
    printf(_("  -f               force update to be done\n"));
    printf(_("  -l XLOGFILE      force minimum WAL starting location for new transaction log\n"));
-   printf(_("  -m XID,OLDEST    set next multitransaction ID and oldest value\n"));
+   printf(_("  -m XID,XID       set next and oldest multitransaction ID\n"));
    printf(_("  -n               no update, just show extracted control values (for testing)\n"));
    printf(_("  -o OID           set next OID\n"));
    printf(_("  -O OFFSET        set next multitransaction offset\n"));