On Wed, Oct 1, 2014 at 7:57 AM, José Luis Tallón <jltal...@adv-solutions.net>
wrote:
>
> [snip]
>
> Please excuse my jumping in, but the EXPECTED syntax is:
>
> CREATE INDEX IF NOT EXISTS .....
>
> whereas your current patch implements:
>
> CREATE [IF NOT EXISTS] INDEX ....
>
>
> if I'm reading the grammar correctly.
>

I think it's not wrong. Look at other CINE that already implemented [1] [2].

But CINE for CREATE TABLE is like your proposal [3] :

CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF
NOT EXISTS ] table_name ...

So, what's the correct/best grammar?

CREATE [ IF NOT EXISTS ] [ UNIQUE ] INDEX index_name

or

CREATE [ UNIQUE ] INDEX [ IF NOT EXISTS ] index_name


> I guess it would be most interesting to implement this minor change for
the next version of the patch. Please do remember to update the
documentation accordingly.
>

I will...


> By the way, you also forgot to remove a previous patch implementing
"namespace_name<DOT>relation_name" for RLS messages. Maybe a rebase is
needed?
>

Sorry... my mistake. Fix attached.


Regards,

[1] http://www.postgresql.org/docs/devel/static/sql-createschema.html
[2] http://www.postgresql.org/docs/devel/static/sql-createsequence.html
[3] http://www.postgresql.org/docs/devel/static/sql-createtable.html

--
Fabrízio de Royes Mello
Consultoria/Coaching PostgreSQL
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diff --git a/doc/src/sgml/ref/create_index.sgml b/doc/src/sgml/ref/create_index.sgml
index e469b17..7886729 100644
--- a/doc/src/sgml/ref/create_index.sgml
+++ b/doc/src/sgml/ref/create_index.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ <replaceable class="parameter">name</replaceable> ] ON <replaceable class="parameter">table_name</replaceable> [ USING <replaceable class="parameter">method</replaceable> ]
+CREATE [ IF NOT EXISTS ] [ UNIQUE ] INDEX [ CONCURRENTLY ] [ <replaceable class="parameter">name</replaceable> ] ON <replaceable class="parameter">table_name</replaceable> [ USING <replaceable class="parameter">method</replaceable> ]
     ( { <replaceable class="parameter">column_name</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ COLLATE <replaceable class="parameter">collation</replaceable> ] [ <replaceable class="parameter">opclass</replaceable> ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [, ...] )
     [ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
@@ -99,6 +99,16 @@ CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ <replaceable class="parameter">name</
 
     <variablelist>
      <varlistentry>
+      <term><literal>IF NOT EXISTS</literal></term>
+      <listitem>
+       <para>
+        Do nothing (except issuing a notice) if a index with the same name
+        already exists.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><literal>UNIQUE</literal></term>
       <listitem>
        <para>
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index ee10594..8905e30 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -697,7 +697,8 @@ index_create(Relation heapRelation,
 			 bool allow_system_table_mods,
 			 bool skip_build,
 			 bool concurrent,
-			 bool is_internal)
+			 bool is_internal,
+			 bool if_not_exists)
 {
 	Oid			heapRelationId = RelationGetRelid(heapRelation);
 	Relation	pg_class;
@@ -773,10 +774,22 @@ index_create(Relation heapRelation,
 		elog(ERROR, "shared relations must be placed in pg_global tablespace");
 
 	if (get_relname_relid(indexRelationName, namespaceId))
+	{
+		if (if_not_exists)
+		{
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							indexRelationName)));
+			heap_close(pg_class, RowExclusiveLock);
+			return InvalidOid;
+		}
+
 		ereport(ERROR,
 				(errcode(ERRCODE_DUPLICATE_TABLE),
 				 errmsg("relation \"%s\" already exists",
 						indexRelationName)));
+	}
 
 	/*
 	 * construct tuple descriptor for index tuples
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index 160f006..5ef6dcc 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -342,7 +342,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 				 rel->rd_rel->reltablespace,
 				 collationObjectId, classObjectId, coloptions, (Datum) 0,
 				 true, false, false, false,
-				 true, false, false, true);
+				 true, false, false, true, false);
 
 	heap_close(toast_rel, NoLock);
 
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 8a1cb4b..a03773b 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -610,7 +610,14 @@ DefineIndex(Oid relationId,
 					 stmt->isconstraint, stmt->deferrable, stmt->initdeferred,
 					 allowSystemTableMods,
 					 skip_build || stmt->concurrent,
-					 stmt->concurrent, !check_rights);
+					 stmt->concurrent, !check_rights,
+					 stmt->if_not_exists);
+
+	if (!OidIsValid(indexRelationId))
+	{
+		heap_close(rel, NoLock);
+		return indexRelationId;
+	}
 
 	/* Add any requested comment */
 	if (stmt->idxcomment != NULL)
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 225756c..39b55db 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -2907,6 +2907,7 @@ _copyIndexStmt(const IndexStmt *from)
 	COPY_SCALAR_FIELD(deferrable);
 	COPY_SCALAR_FIELD(initdeferred);
 	COPY_SCALAR_FIELD(concurrent);
+	COPY_SCALAR_FIELD(if_not_exists);
 
 	return newnode;
 }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 905468e..4cf91e0 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1210,6 +1210,7 @@ _equalIndexStmt(const IndexStmt *a, const IndexStmt *b)
 	COMPARE_SCALAR_FIELD(deferrable);
 	COMPARE_SCALAR_FIELD(initdeferred);
 	COMPARE_SCALAR_FIELD(concurrent);
+	COMPARE_SCALAR_FIELD(if_not_exists);
 
 	return true;
 }
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 77d2f29..03a04af 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -6427,20 +6427,32 @@ defacl_privilege_target:
  * willing to make TABLESPACE a fully reserved word.
  *****************************************************************************/
 
-IndexStmt:	CREATE opt_unique INDEX opt_concurrently opt_index_name
+IndexStmt:	CREATE opt_if_not_exists opt_unique INDEX opt_concurrently opt_index_name
 			ON qualified_name access_method_clause '(' index_params ')'
 			opt_reloptions OptTableSpace where_clause
 				{
 					IndexStmt *n = makeNode(IndexStmt);
-					n->unique = $2;
-					n->concurrent = $4;
-					n->idxname = $5;
-					n->relation = $7;
-					n->accessMethod = $8;
-					n->indexParams = $10;
-					n->options = $12;
-					n->tableSpace = $13;
-					n->whereClause = $14;
+					n->if_not_exists = $2;
+					n->unique = $3;
+					n->concurrent = $5;
+					n->idxname = $6;
+
+					/*
+					 * Throw an exception when IF NOT EXISTS is used without a named
+					 * index
+					 */
+					if (n->if_not_exists && n->idxname == NULL)
+						ereport(ERROR,
+								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+								 errmsg("IF NOT EXISTS requires that you name the index."),
+								 parser_errposition(@2)));
+
+					n->relation = $8;
+					n->accessMethod = $9;
+					n->indexParams = $11;
+					n->options = $13;
+					n->tableSpace = $14;
+					n->whereClause = $15;
 					n->excludeOpNames = NIL;
 					n->idxcomment = NULL;
 					n->indexOid = InvalidOid;
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 12811a8..076ff8d 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -2803,7 +2803,7 @@ getRowSecurity(Archive *fout, TableInfo tblinfo[], int numTables)
 			continue;
 
 		if (g_verbose)
-			write_msg(NULL, "reading row-security enabled for table \"%s\"",
+			write_msg(NULL, "reading row-security enabled for table \"%s\"\n",
 					  tbinfo->dobj.name);
 
 		/*
diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h
index 006b180..098ac7d 100644
--- a/src/include/catalog/index.h
+++ b/src/include/catalog/index.h
@@ -60,7 +60,8 @@ extern Oid index_create(Relation heapRelation,
 			 bool allow_system_table_mods,
 			 bool skip_build,
 			 bool concurrent,
-			 bool is_internal);
+			 bool is_internal,
+			 bool if_not_exists);
 
 extern void index_constraint_create(Relation heapRelation,
 						Oid indexRelationId,
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index f3aa69e..a326dc4 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2255,6 +2255,7 @@ typedef struct IndexStmt
 	bool		deferrable;		/* is the constraint DEFERRABLE? */
 	bool		initdeferred;	/* is the constraint INITIALLY DEFERRED? */
 	bool		concurrent;		/* should this be a concurrent index build? */
+	bool		if_not_exists;	/* just do nothing if index already exists */
 } IndexStmt;
 
 /* ----------------------
diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index a2bef7a..0c48d58 100644
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -6,6 +6,12 @@
 -- BTREE
 --
 CREATE INDEX onek_unique1 ON onek USING btree(unique1 int4_ops);
+CREATE IF NOT EXISTS INDEX onek_unique1 ON onek USING btree(unique1 int4_ops);
+NOTICE:  relation "onek_unique1" already exists, skipping
+CREATE IF NOT EXISTS INDEX ON onek USING btree(unique1 int4_ops);
+ERROR:  IF NOT EXISTS requires that you name the index.
+LINE 1: CREATE IF NOT EXISTS INDEX ON onek USING btree(unique1 int4_...
+               ^
 CREATE INDEX onek_unique2 ON onek USING btree(unique2 int4_ops);
 CREATE INDEX onek_hundred ON onek USING btree(hundred int4_ops);
 CREATE INDEX onek_stringu1 ON onek USING btree(stringu1 name_ops);
@@ -2290,10 +2296,14 @@ create unique index hash_f8_index_3 on hash_f8_heap(random) where seqno > 1000;
 CREATE TABLE concur_heap (f1 text, f2 text);
 -- empty table
 CREATE INDEX CONCURRENTLY concur_index1 ON concur_heap(f2,f1);
+CREATE IF NOT EXISTS INDEX CONCURRENTLY concur_index1 ON concur_heap(f2,f1);
+NOTICE:  relation "concur_index1" already exists, skipping
 INSERT INTO concur_heap VALUES  ('a','b');
 INSERT INTO concur_heap VALUES  ('b','b');
 -- unique index
 CREATE UNIQUE INDEX CONCURRENTLY concur_index2 ON concur_heap(f1);
+CREATE IF NOT EXISTS UNIQUE INDEX CONCURRENTLY concur_index2 ON concur_heap(f1);
+NOTICE:  relation "concur_index2" already exists, skipping
 -- check if constraint is set up properly to be enforced
 INSERT INTO concur_heap VALUES ('b','x');
 ERROR:  duplicate key value violates unique constraint "concur_index2"
diff --git a/src/test/regress/sql/create_index.sql b/src/test/regress/sql/create_index.sql
index d4d24ef..973a709 100644
--- a/src/test/regress/sql/create_index.sql
+++ b/src/test/regress/sql/create_index.sql
@@ -8,6 +8,10 @@
 --
 CREATE INDEX onek_unique1 ON onek USING btree(unique1 int4_ops);
 
+CREATE IF NOT EXISTS INDEX onek_unique1 ON onek USING btree(unique1 int4_ops);
+
+CREATE IF NOT EXISTS INDEX ON onek USING btree(unique1 int4_ops);
+
 CREATE INDEX onek_unique2 ON onek USING btree(unique2 int4_ops);
 
 CREATE INDEX onek_hundred ON onek USING btree(hundred int4_ops);
@@ -711,10 +715,12 @@ create unique index hash_f8_index_3 on hash_f8_heap(random) where seqno > 1000;
 CREATE TABLE concur_heap (f1 text, f2 text);
 -- empty table
 CREATE INDEX CONCURRENTLY concur_index1 ON concur_heap(f2,f1);
+CREATE IF NOT EXISTS INDEX CONCURRENTLY concur_index1 ON concur_heap(f2,f1);
 INSERT INTO concur_heap VALUES  ('a','b');
 INSERT INTO concur_heap VALUES  ('b','b');
 -- unique index
 CREATE UNIQUE INDEX CONCURRENTLY concur_index2 ON concur_heap(f1);
+CREATE IF NOT EXISTS UNIQUE INDEX CONCURRENTLY concur_index2 ON concur_heap(f1);
 -- check if constraint is set up properly to be enforced
 INSERT INTO concur_heap VALUES ('b','x');
 -- check if constraint is enforced properly at build time
-- 
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