Re: pg_migrator and handling dropped columns

Applied.

---------------------------------------------------------------------------

Bruce Momjian wrote:
> Peter Eisentraut wrote:
> > Tom Lane wrote:
> > >> Is this acceptable to everyone?  We could name the option
> > >> -u/--upgrade-compatible.
> > > 
> > > If the switch is specifically for pg_upgrade support (enabling this as
> > > well as any other hacks we find necessary), which seems like a good
> > > idea, then don't chew up a short option letter for it.  There should be
> > > a long form only.
> > 
> > Note that pg_dump's output is already upgrade compatible.  That's what 
> > pg_dump is often used for after all.  I believe what we are after here 
> > is something like "in-place upgrade compatible" or "upgrade binary 
> > compatible".
> > 
> > > And probably not even list it in the user documentation.
> > 
> > I think we should still list it somewhere and say it is for use by 
> > in-place upgrade utilities.  It will only confuse people if it is not 
> > documented at all.
> 
> OK, I have completed the patch;  attached.
> 
> I ran into a little problem, as documented by this comment in
> catalog/heap.c:
> 
>         /*
>          * Set the type OID to invalid.  A dropped attribute's type link
>          * cannot be relied on (once the attribute is dropped, the type might
>          * be too). Fortunately we do not need the type row --- the only
>          * really essential information is the type's typlen and typalign,
>          * which are preserved in the attribute's attlen and attalign.  We set
>          * atttypid to zero here as a means of catching code that incorrectly
>          * expects it to be valid.
>          */
> 
> Basically, drop column zeros pg_attribute.atttypid, and there doesn't
> seem to be enough information left in pg_attribute to guess the typid
> that, combined with atttypmod, would restore the proper values for
> pg_attribute.atttypid and pg_attribute.attalign.  Therefore, I just
> brute-forced an UPDATE into dump to set the values properly after
> dropping the fake TEXT column.
> 
> I did a minimal documentation addition by adding something to the
> "Notes" section of the manual pages.
> 
> Here is what a dump of a table with dropped columns looks like:
> 
>     --
>     -- Name: test; Type: TABLE; Schema: public; Owner: postgres; Tablespace:
>     --
>     
>     CREATE TABLE test (
>         x integer,
>         "........pg.dropped.2........" TEXT
>     );
>     ALTER TABLE ONLY test DROP COLUMN "........pg.dropped.2........";
>     
>     -- For binary upgrade, recreate dropped column's length and alignment.
>     UPDATE pg_attribute
>     SET attlen = -1, attalign = 'i'
>     WHERE   attname = '........pg.dropped.2........'
>             AND attrelid =
>             (
>                     SELECT oid
>                     FROM pg_class
>                     WHERE   relnamespace = (SELECT oid FROM pg_namespace WHERE nspname = CURRENT_SCHEMA)
>                             AND relname = 'test'
>             );
>     
>     ALTER TABLE public.test OWNER TO postgres;
> 
> -- 
>   Bruce Momjian  <bruce@momjian.us>        http://momjian.us
>   EnterpriseDB                             http://enterprisedb.com
> 
>   + If your life is a hard drive, Christ can be your backup. +

[ text/x-diff is unsupported, treating like TEXT/PLAIN ]

> Index: doc/src/sgml/ref/pg_dump.sgml
> ===================================================================
> RCS file: /cvsroot/pgsql/doc/src/sgml/ref/pg_dump.sgml,v
> retrieving revision 1.109
> diff -c -c -r1.109 pg_dump.sgml
> *** doc/src/sgml/ref/pg_dump.sgml    10 Feb 2009 00:55:21 -0000    1.109
> --- doc/src/sgml/ref/pg_dump.sgml    17 Feb 2009 01:57:10 -0000
> ***************
> *** 827,832 ****
> --- 827,837 ----
>      editing of the dump file might be required.
>     </para>
>   
> +   <para>
> +    <application>pg_dump</application> also supports a
> +    <literal>--binary-upgrade</> option for upgrade utility usage.
> +   </para>
> + 
>    </refsect1>
>   
>    <refsect1 id="pg-dump-examples">
> Index: doc/src/sgml/ref/pg_dumpall.sgml
> ===================================================================
> RCS file: /cvsroot/pgsql/doc/src/sgml/ref/pg_dumpall.sgml,v
> retrieving revision 1.75
> diff -c -c -r1.75 pg_dumpall.sgml
> *** doc/src/sgml/ref/pg_dumpall.sgml    7 Feb 2009 14:31:30 -0000    1.75
> --- doc/src/sgml/ref/pg_dumpall.sgml    17 Feb 2009 01:57:10 -0000
> ***************
> *** 489,494 ****
> --- 489,499 ----
>      locations.
>     </para>
>   
> +   <para>
> +    <application>pg_dump</application> also supports a
> +    <literal>--binary-upgrade</> option for upgrade utility usage.
> +   </para>
> + 
>    </refsect1>
>   
>   
> Index: src/bin/pg_dump/pg_dump.c
> ===================================================================
> RCS file: /cvsroot/pgsql/src/bin/pg_dump/pg_dump.c,v
> retrieving revision 1.521
> diff -c -c -r1.521 pg_dump.c
> *** src/bin/pg_dump/pg_dump.c    16 Feb 2009 23:06:55 -0000    1.521
> --- src/bin/pg_dump/pg_dump.c    17 Feb 2009 01:57:10 -0000
> ***************
> *** 99,104 ****
> --- 99,106 ----
>   /* default, if no "inclusion" switches appear, is to dump everything */
>   static bool include_everything = true;
>   
> + static int    binary_upgrade = 0;
> + 
>   char        g_opaque_type[10];    /* name for the opaque type */
>   
>   /* placeholders for the delimiters for comments */
> ***************
> *** 236,242 ****
>       static int  outputNoTablespaces = 0;
>       static int    use_setsessauth = 0;
>   
> !     static struct option long_options[] = {
>           {"data-only", no_argument, NULL, 'a'},
>           {"blobs", no_argument, NULL, 'b'},
>           {"clean", no_argument, NULL, 'c'},
> --- 238,245 ----
>       static int  outputNoTablespaces = 0;
>       static int    use_setsessauth = 0;
>   
> !     struct option long_options[] = {
> !         {"binary-upgrade", no_argument, &binary_upgrade, 1},    /* not documented */
>           {"data-only", no_argument, NULL, 'a'},
>           {"blobs", no_argument, NULL, 'b'},
>           {"clean", no_argument, NULL, 'c'},
> ***************
> *** 4611,4616 ****
> --- 4614,4621 ----
>       int            i_attnotnull;
>       int            i_atthasdef;
>       int            i_attisdropped;
> +     int            i_attlen;
> +     int            i_attalign;
>       int            i_attislocal;
>       PGresult   *res;
>       int            ntups;
> ***************
> *** 4655,4661 ****
>               appendPQExpBuffer(q, "SELECT a.attnum, a.attname, a.atttypmod, "
>                                    "a.attstattarget, a.attstorage, t.typstorage, "
>                                      "a.attnotnull, a.atthasdef, a.attisdropped, "
> !                                  "a.attislocal, "
>                      "pg_catalog.format_type(t.oid,a.atttypmod) AS atttypname "
>                "FROM pg_catalog.pg_attribute a LEFT JOIN pg_catalog.pg_type t "
>                                 "ON a.atttypid = t.oid "
> --- 4660,4666 ----
>               appendPQExpBuffer(q, "SELECT a.attnum, a.attname, a.atttypmod, "
>                                    "a.attstattarget, a.attstorage, t.typstorage, "
>                                      "a.attnotnull, a.atthasdef, a.attisdropped, "
> !                                    "a.attlen, a.attalign, a.attislocal, "
>                      "pg_catalog.format_type(t.oid,a.atttypmod) AS atttypname "
>                "FROM pg_catalog.pg_attribute a LEFT JOIN pg_catalog.pg_type t "
>                                 "ON a.atttypid = t.oid "
> ***************
> *** 4674,4680 ****
>               appendPQExpBuffer(q, "SELECT a.attnum, a.attname, "
>                                 "a.atttypmod, -1 AS attstattarget, a.attstorage, "
>                                 "t.typstorage, a.attnotnull, a.atthasdef, "
> !                               "false AS attisdropped, false AS attislocal, "
>                                 "format_type(t.oid,a.atttypmod) AS atttypname "
>                                 "FROM pg_attribute a LEFT JOIN pg_type t "
>                                 "ON a.atttypid = t.oid "
> --- 4679,4686 ----
>               appendPQExpBuffer(q, "SELECT a.attnum, a.attname, "
>                                 "a.atttypmod, -1 AS attstattarget, a.attstorage, "
>                                 "t.typstorage, a.attnotnull, a.atthasdef, "
> !                               "false AS attisdropped, 0 AS attlen, "
> !                               "' ' AS attalign, false AS attislocal, "
>                                 "format_type(t.oid,a.atttypmod) AS atttypname "
>                                 "FROM pg_attribute a LEFT JOIN pg_type t "
>                                 "ON a.atttypid = t.oid "
> ***************
> *** 4690,4696 ****
>                                 "-1 AS attstattarget, attstorage, "
>                                 "attstorage AS typstorage, "
>                                 "attnotnull, atthasdef, false AS attisdropped, "
> !                               "false AS attislocal, "
>                                 "(SELECT typname FROM pg_type WHERE oid = atttypid) AS atttypname "
>                                 "FROM pg_attribute a "
>                                 "WHERE attrelid = '%u'::oid "
> --- 4696,4703 ----
>                                 "-1 AS attstattarget, attstorage, "
>                                 "attstorage AS typstorage, "
>                                 "attnotnull, atthasdef, false AS attisdropped, "
> !                               "0 AS attlen, ' ' AS attalign, "
> !                                "false AS attislocal, "
>                                 "(SELECT typname FROM pg_type WHERE oid = atttypid) AS atttypname "
>                                 "FROM pg_attribute a "
>                                 "WHERE attrelid = '%u'::oid "
> ***************
> *** 4714,4719 ****
> --- 4721,4728 ----
>           i_attnotnull = PQfnumber(res, "attnotnull");
>           i_atthasdef = PQfnumber(res, "atthasdef");
>           i_attisdropped = PQfnumber(res, "attisdropped");
> +         i_attlen = PQfnumber(res, "attlen");
> +         i_attalign = PQfnumber(res, "attalign");
>           i_attislocal = PQfnumber(res, "attislocal");
>   
>           tbinfo->numatts = ntups;
> ***************
> *** 4724,4729 ****
> --- 4733,4740 ----
>           tbinfo->attstorage = (char *) malloc(ntups * sizeof(char));
>           tbinfo->typstorage = (char *) malloc(ntups * sizeof(char));
>           tbinfo->attisdropped = (bool *) malloc(ntups * sizeof(bool));
> +         tbinfo->attlen = (int *) malloc(ntups * sizeof(int));
> +         tbinfo->attalign = (char *) malloc(ntups * sizeof(char));
>           tbinfo->attislocal = (bool *) malloc(ntups * sizeof(bool));
>           tbinfo->notnull = (bool *) malloc(ntups * sizeof(bool));
>           tbinfo->attrdefs = (AttrDefInfo **) malloc(ntups * sizeof(AttrDefInfo *));
> ***************
> *** 4747,4752 ****
> --- 4758,4765 ----
>               tbinfo->attstorage[j] = *(PQgetvalue(res, j, i_attstorage));
>               tbinfo->typstorage[j] = *(PQgetvalue(res, j, i_typstorage));
>               tbinfo->attisdropped[j] = (PQgetvalue(res, j, i_attisdropped)[0] == 't');
> +             tbinfo->attlen[j] = atoi(PQgetvalue(res, j, i_attlen));
> +             tbinfo->attalign[j] = *(PQgetvalue(res, j, i_attalign));
>               tbinfo->attislocal[j] = (PQgetvalue(res, j, i_attislocal)[0] == 't');
>               tbinfo->notnull[j] = (PQgetvalue(res, j, i_attnotnull)[0] == 't');
>               tbinfo->attrdefs[j] = NULL; /* fix below */
> ***************
> *** 4760,4765 ****
> --- 4773,4793 ----
>   
>           PQclear(res);
>   
> + 
> +         /*
> +          *    ALTER TABLE DROP COLUMN clears pg_attribute.atttypid, so we
> +          *    set the column data type to 'TEXT;  we will later drop the
> +          *    column.
> +          */
> +         if (binary_upgrade)
> +         {
> +             for (j = 0; j < ntups; j++)
> +             {
> +                 if (tbinfo->attisdropped[j])
> +                     tbinfo->atttypnames[j] = strdup("TEXT");
> +             }
> +         }
> +             
>           /*
>            * Get info about column defaults
>            */
> ***************
> *** 9680,9686 ****
>           for (j = 0; j < tbinfo->numatts; j++)
>           {
>               /* Is this one of the table's own attrs, and not dropped ? */
> !             if (!tbinfo->inhAttrs[j] && !tbinfo->attisdropped[j])
>               {
>                   /* Format properly if not first attr */
>                   if (actual_atts > 0)
> --- 9708,9715 ----
>           for (j = 0; j < tbinfo->numatts; j++)
>           {
>               /* Is this one of the table's own attrs, and not dropped ? */
> !             if (!tbinfo->inhAttrs[j] &&
> !                 (!tbinfo->attisdropped[j] || binary_upgrade))
>               {
>                   /* Format properly if not first attr */
>                   if (actual_atts > 0)
> ***************
> *** 9786,9791 ****
> --- 9815,9867 ----
>   
>           appendPQExpBuffer(q, ";\n");
>   
> +         /*
> +          * For binary-compatible heap files, we create dropped columns
> +          * above and drop them here.
> +          */
> +         if (binary_upgrade)
> +         {
> +             for (j = 0; j < tbinfo->numatts; j++)
> +             {
> +                 if (tbinfo->attisdropped[j])
> +                 {
> +                     appendPQExpBuffer(q, "ALTER TABLE ONLY %s ",
> +                                       fmtId(tbinfo->dobj.name));
> +                     appendPQExpBuffer(q, "DROP COLUMN %s;\n",
> +                                       fmtId(tbinfo->attnames[j]));
> + 
> +                     /*
> +                      *    ALTER TABLE DROP COLUMN clears pg_attribute.atttypid,
> +                      *    so we have to set pg_attribute.attlen and
> +                      *    pg_attribute.attalign values because that is what
> +                      *    is used to skip over dropped columns in the heap tuples.
> +                      *    We have atttypmod, but it seems impossible to know the
> +                      *    correct data type that will yield pg_attribute values
> +                      *    that match the old installation.
> +                      *    See comment in backend/catalog/heap.c::RemoveAttributeById()
> +                      */
> +                     appendPQExpBuffer(q, "\n-- For binary upgrade, recreate dropped column's length and
alignment.\n");
> +                     appendPQExpBuffer(q, "UPDATE pg_attribute\n"
> +                                          "SET attlen = %d, "
> +                                          "attalign = '%c'\n"
> +                                          "WHERE    attname = '%s'\n"
> +                                          "    AND attrelid = \n"
> +                                          "    (\n"
> +                                          "        SELECT oid\n"
> +                                          "        FROM pg_class\n"
> +                                          "        WHERE    relnamespace = "
> +                                          "(SELECT oid FROM pg_namespace "
> +                                          "WHERE nspname = CURRENT_SCHEMA)\n"
> +                                          "            AND relname = '%s'\n"
> +                                          "    );",
> +                                          tbinfo->attlen[j],
> +                                          tbinfo->attalign[j],
> +                                          tbinfo->attnames[j],
> +                                          tbinfo->dobj.name);
> +                 }
> +             }
> +         }
> +     
>           /* Loop dumping statistics and storage statements */
>           for (j = 0; j < tbinfo->numatts; j++)
>           {
> Index: src/bin/pg_dump/pg_dump.h
> ===================================================================
> RCS file: /cvsroot/pgsql/src/bin/pg_dump/pg_dump.h,v
> retrieving revision 1.150
> diff -c -c -r1.150 pg_dump.h
> *** src/bin/pg_dump/pg_dump.h    2 Feb 2009 19:31:39 -0000    1.150
> --- src/bin/pg_dump/pg_dump.h    17 Feb 2009 01:57:10 -0000
> ***************
> *** 245,250 ****
> --- 245,252 ----
>       char       *attstorage;        /* attribute storage scheme */
>       char       *typstorage;        /* type storage scheme */
>       bool       *attisdropped;    /* true if attr is dropped; don't dump it */
> +     int           *attlen;            /* attribute length, used by binary_upgrade */
> +     char       *attalign;        /* attribute align, used by binary_upgrade */
>       bool       *attislocal;        /* true if attr has local definition */
>   
>       /*
> Index: src/bin/pg_dump/pg_dumpall.c
> ===================================================================
> RCS file: /cvsroot/pgsql/src/bin/pg_dump/pg_dumpall.c,v
> retrieving revision 1.113
> diff -c -c -r1.113 pg_dumpall.c
> *** src/bin/pg_dump/pg_dumpall.c    22 Jan 2009 20:16:08 -0000    1.113
> --- src/bin/pg_dump/pg_dumpall.c    17 Feb 2009 01:57:10 -0000
> ***************
> *** 90,97 ****
>       const char *std_strings;
>       int            c,
>                   ret;
>   
> !     static struct option long_options[] = {
>           {"data-only", no_argument, NULL, 'a'},
>           {"clean", no_argument, NULL, 'c'},
>           {"inserts", no_argument, NULL, 'd'},
> --- 90,99 ----
>       const char *std_strings;
>       int            c,
>                   ret;
> +     int            binary_upgrade = 0;
>   
> !     struct option long_options[] = {
> !         {"binary-upgrade", no_argument, &binary_upgrade, 1},    /* not documented */
>           {"data-only", no_argument, NULL, 'a'},
>           {"clean", no_argument, NULL, 'c'},
>           {"inserts", no_argument, NULL, 'd'},
> ***************
> *** 310,315 ****
> --- 312,319 ----
>       }
>   
>       /* Add long options to the pg_dump argument list */
> +     if (binary_upgrade)
> +         appendPQExpBuffer(pgdumpopts, " --binary-upgrade");
>       if (disable_dollar_quoting)
>           appendPQExpBuffer(pgdumpopts, " --disable-dollar-quoting");
>       if (disable_triggers)

> 
> -- 
> Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-hackers

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + If your life is a hard drive, Christ can be your backup. +