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pg_dump et al: Add --if-exists option 

This option makes pg_dump, pg_dumpall and pg_restore inject an IF EXISTS
clause to each DROP command they emit.  (In pg_dumpall, the clause is
not added to individual objects drops, but rather to the CREATE DATABASE
commands, as well as CREATE ROLE and CREATE TABLESPACE.)

This allows for a better user dump experience when using --clean in case
some objects do not already exist.  Per bug #7873 by Dave Rolsky.

Author: Pavel Stěhule
Reviewed-by: Jeevan Chalke, Álvaro Herrera, Josh Kupershmidt
This commit is contained in:
Alvaro Herrera 2014-03-03 15:02:18 -03:00
parent 34c6d9611d
commit 9067310cc5
8 changed files with 146 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
doc/src/sgml/ref/pg_dump.sgml
View File

@ -145,7 +145,8 @@ PostgreSQL documentation
<para>
Output commands to clean (drop)
database objects prior to outputting the commands for creating them.
(Restore might generate some harmless error messages, if any objects
(Unless <option>--if-exists</> is also specified,
restore might generate some harmless error messages, if any objects
were not present in the destination database.)
</para>
@ -649,6 +650,17 @@ PostgreSQL documentation
</listitem>
</varlistentry>
<varlistentry>
<term><option>--if-exists</option></term>
<listitem>
<para>
Use conditional commands (i.e. add an <literal>IF EXISTS</literal>
clause) when cleaning database objects. This option is not valid
unless <option>--clean</> is also specified.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--disable-dollar-quoting</></term>
<listitem>

11
doc/src/sgml/ref/pg_dumpall.sgml
View File

@ -300,6 +300,17 @@ PostgreSQL documentation
</listitem>
</varlistentry>
<varlistentry>
<term><option>--if-exists</option></term>
<listitem>
<para>
Use conditional commands (i.e. add an <literal>IF EXISTS</literal>
clause) to clean databases and other objects. This option is not valid
unless <option>--clean</> is also specified.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--inserts</option></term>
<listitem>

14
doc/src/sgml/ref/pg_restore.sgml
View File

@ -109,7 +109,8 @@
<listitem>
<para>
Clean (drop) database objects before recreating them.
(This might generate some harmless error messages, if any objects
(Unless <option>--if-exists</> is used,
this might generate some harmless error messages, if any objects
were not present in the destination database.)
</para>
</listitem>
@ -489,6 +490,17 @@
</listitem>
</varlistentry>
<varlistentry>
<term><option>--if-exists</option></term>
<listitem>
<para>
Use conditional commands (i.e. add an <literal>IF EXISTS</literal>
clause) when cleaning database objects. This option is not valid
unless <option>--clean</> is also specified.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--no-data-for-failed-tables</option></term>
<listitem>

1
src/bin/pg_dump/pg_backup.h
View File

@ -113,6 +113,7 @@ typedef struct _restoreOptions
char *superuser; /* Username to use as superuser */
char *use_role; /* Issue SET ROLE to this */
int dropSchema;
int if_exists;
const char *filename;
int dataOnly;
int schemaOnly;

73
src/bin/pg_dump/pg_backup_archiver.c
View File

@ -413,8 +413,77 @@ RestoreArchive(Archive *AHX)
/* Select owner and schema as necessary */
_becomeOwner(AH, te);
_selectOutputSchema(AH, te->namespace);
/* Drop it */
ahprintf(AH, "%s", te->dropStmt);
/*
* Now emit the DROP command, if the object has one. Note we
* don't necessarily emit it verbatim; at this point we add an
* appropriate IF EXISTS clause, if the user requested it.
*/
if (*te->dropStmt != '\0')
{
if (!ropt->if_exists)
{
/* No --if-exists? Then just use the original */
ahprintf(AH, "%s", te->dropStmt);
}
else
{
char buffer[40];
char *mark;
char *dropStmt = pg_strdup(te->dropStmt);
char *dropStmtPtr = dropStmt;
PQExpBuffer ftStmt = createPQExpBuffer();
/*
* Need to inject IF EXISTS clause after ALTER TABLE
* part in ALTER TABLE .. DROP statement
*/
if (strncmp(dropStmt, "ALTER TABLE", 11) == 0)
{
appendPQExpBuffer(ftStmt,
"ALTER TABLE IF EXISTS");
dropStmt = dropStmt + 11;
}
/*
* ALTER TABLE..ALTER COLUMN..DROP DEFAULT does not
* support the IF EXISTS clause, and therefore we
* simply emit the original command for such objects.
* For other objects, we need to extract the first part
* of the DROP which includes the object type. Most of
* the time this matches te->desc, so search for that;
* however for the different kinds of CONSTRAINTs, we
* know to search for hardcoded "DROP CONSTRAINT"
* instead.
*/
if (strcmp(te->desc, "DEFAULT") == 0)
appendPQExpBuffer(ftStmt, "%s", dropStmt);
else
{
if (strcmp(te->desc, "CONSTRAINT") == 0 ||
strcmp(te->desc, "CHECK CONSTRAINT") == 0 ||
strcmp(te->desc, "FK CONSTRAINT") == 0)
strcpy(buffer, "DROP CONSTRAINT");
else
snprintf(buffer, sizeof(buffer), "DROP %s",
te->desc);
mark = strstr(dropStmt, buffer);
Assert(mark != NULL);
*mark = '\0';
appendPQExpBuffer(ftStmt, "%s%s IF EXISTS%s",
dropStmt, buffer,
mark + strlen(buffer));
}
ahprintf(AH, "%s", ftStmt->data);
destroyPQExpBuffer(ftStmt);
pg_free(dropStmtPtr);
}
}
}
}

7
src/bin/pg_dump/pg_dump.c
View File

@ -132,6 +132,7 @@ static int binary_upgrade = 0;
static int disable_dollar_quoting = 0;
static int dump_inserts = 0;
static int column_inserts = 0;
static int if_exists = 0;
static int no_security_labels = 0;
static int no_synchronized_snapshots = 0;
static int no_unlogged_table_data = 0;
@ -345,6 +346,7 @@ main(int argc, char **argv)
{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
{"disable-triggers", no_argument, &disable_triggers, 1},
{"exclude-table-data", required_argument, NULL, 4},
{"if-exists", no_argument, &if_exists, 1},
{"inserts", no_argument, &dump_inserts, 1},
{"lock-wait-timeout", required_argument, NULL, 2},
{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
@ -573,6 +575,9 @@ main(int argc, char **argv)
exit_nicely(1);
}
if (if_exists && !outputClean)
exit_horribly(NULL, "option --if-exists requires -c/--clean option\n");
/* Identify archive format to emit */
archiveFormat = parseArchiveFormat(format, &archiveMode);
@ -805,6 +810,7 @@ main(int argc, char **argv)
ropt->dropSchema = outputClean;
ropt->dataOnly = dataOnly;
ropt->schemaOnly = schemaOnly;
ropt->if_exists = if_exists;
ropt->dumpSections = dumpSections;
ropt->aclsSkip = aclsSkip;
ropt->superuser = outputSuperuser;
@ -886,6 +892,7 @@ help(const char *progname)
printf(_(" --disable-dollar-quoting disable dollar quoting, use SQL standard quoting\n"));
printf(_(" --disable-triggers disable triggers during data-only restore\n"));
printf(_(" --exclude-table-data=TABLE do NOT dump data for the named table(s)\n"));
printf(_(" --if-exists use IF EXISTS when dropping objects\n"));
printf(_(" --inserts dump data as INSERT commands, rather than COPY\n"));
printf(_(" --no-security-labels do not dump security label assignments\n"));
printf(_(" --no-synchronized-snapshots do not use synchronized snapshots in parallel jobs\n"));

22
src/bin/pg_dump/pg_dumpall.c
View File

@ -73,6 +73,7 @@ static int binary_upgrade = 0;
static int column_inserts = 0;
static int disable_dollar_quoting = 0;
static int disable_triggers = 0;
static int if_exists = 0;
static int inserts = 0;
static int no_tablespaces = 0;
static int use_setsessauth = 0;
@ -119,6 +120,7 @@ main(int argc, char *argv[])
{"column-inserts", no_argument, &column_inserts, 1},
{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
{"disable-triggers", no_argument, &disable_triggers, 1},
{"if-exists", no_argument, &if_exists, 1},
{"inserts", no_argument, &inserts, 1},
{"lock-wait-timeout", required_argument, NULL, 2},
{"no-tablespaces", no_argument, &no_tablespaces, 1},
@ -334,6 +336,13 @@ main(int argc, char *argv[])
exit_nicely(1);
}
if (if_exists && !output_clean)
{
fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
progname);
exit_nicely(1);
}
if (roles_only && tablespaces_only)
{
fprintf(stderr, _("%s: options -r/--roles-only and -t/--tablespaces-only cannot be used together\n"),
@ -564,6 +573,7 @@ help(void)
printf(_(" --column-inserts dump data as INSERT commands with column names\n"));
printf(_(" --disable-dollar-quoting disable dollar quoting, use SQL standard quoting\n"));
printf(_(" --disable-triggers disable triggers during data-only restore\n"));
printf(_(" --if-exists use IF EXISTS when dropping objects\n"));
printf(_(" --inserts dump data as INSERT commands, rather than COPY\n"));
printf(_(" --no-security-labels do not dump security label assignments\n"));
printf(_(" --no-tablespaces do not dump tablespace assignments\n"));
@ -624,7 +634,9 @@ dropRoles(PGconn *conn)
rolename = PQgetvalue(res, i, i_rolname);
fprintf(OPF, "DROP ROLE %s;\n", fmtId(rolename));
fprintf(OPF, "DROP ROLE %s%s;\n",
if_exists ? "IF EXISTS " : "",
fmtId(rolename));
}
PQclear(res);
@ -994,7 +1006,9 @@ dropTablespaces(PGconn *conn)
{
char *spcname = PQgetvalue(res, i, 0);
fprintf(OPF, "DROP TABLESPACE %s;\n", fmtId(spcname));
fprintf(OPF, "DROP TABLESPACE %s%s;\n",
if_exists ? "IF EXISTS " : "",
fmtId(spcname));
}
PQclear(res);
@ -1148,7 +1162,9 @@ dropDBs(PGconn *conn)
if (strcmp(dbname, "template1") != 0 &&
strcmp(dbname, "postgres") != 0)
{
fprintf(OPF, "DROP DATABASE %s;\n", fmtId(dbname));
fprintf(OPF, "DROP DATABASE %s%s;\n",
if_exists ? "IF EXISTS " : "",
fmtId(dbname));
}
}

11
src/bin/pg_dump/pg_restore.c
View File

@ -70,6 +70,7 @@ main(int argc, char **argv)
Archive *AH;
char *inputFileSpec;
static int disable_triggers = 0;
static int if_exists = 0;
static int no_data_for_failed_tables = 0;
static int outputNoTablespaces = 0;
static int use_setsessauth = 0;
@ -110,6 +111,7 @@ main(int argc, char **argv)
* the following options don't have an equivalent short option letter
*/
{"disable-triggers", no_argument, &disable_triggers, 1},
{"if-exists", no_argument, &if_exists, 1},
{"no-data-for-failed-tables", no_argument, &no_data_for_failed_tables, 1},
{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
{"role", required_argument, NULL, 2},
@ -336,6 +338,14 @@ main(int argc, char **argv)
opts->use_setsessauth = use_setsessauth;
opts->no_security_labels = no_security_labels;
if (if_exists && !opts->dropSchema)
{
fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
progname);
exit_nicely(1);
}
opts->if_exists = if_exists;
if (opts->formatName)
{
switch (opts->formatName[0])
@ -450,6 +460,7 @@ usage(const char *progname)
printf(_(" -x, --no-privileges skip restoration of access privileges (grant/revoke)\n"));
printf(_(" -1, --single-transaction restore as a single transaction\n"));
printf(_(" --disable-triggers disable triggers during data-only restore\n"));
printf(_(" --if-exists use IF EXISTS when dropping objects\n"));
printf(_(" --no-data-for-failed-tables do not restore data of tables that could not be\n"
" created\n"));
printf(_(" --no-security-labels do not restore security labels\n"));