[CF 5667] v6 - support create index on virtual generated column.

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https://commitfest.postgresql.org/patch/5667

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Patch(es): https://www.postgresql.org/message-id/CACJufxHT-1a-uP9pEq6rpuvq8mS0V0xOHr30R4THsDeo5DyTUA@mail.gmail.com
Author(s): Jian He

Author: Commitfest Bot

contrib/pageinspect/expected/btree.out

@@ -183,6 +183,17 @@ tids       |
 
 SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 2));
 ERROR:  block number 2 is out of range for relation "test1_a_idx"
+---test index over virtual generated column
+CREATE TABLE test4(a int, b int GENERATED ALWAYS AS (a + 1), c text);
+INSERT INTO test4(a,c) VALUES (10,11), (10,11);
+CREATE INDEX test4_b_idx ON test4 USING btree (b);
+CREATE INDEX test4_a_1_idx ON test4 USING btree ((a+1));
+--expect return zero row
+SELECT * FROM bt_page_items('test4_b_idx', 1)
+EXCEPT ALL
+SELECT * FROM bt_page_items('test4_a_1_idx', 1);
+(0 rows)
+
 -- Failure when using a non-btree index.
 CREATE INDEX test1_a_hash ON test1 USING hash(a);
 SELECT bt_metap('test1_a_hash');

contrib/pageinspect/sql/btree.sql

@@ -32,6 +32,16 @@ SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 0));
 SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 1));
 SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 2));
 
+---test index over virtual generated column
+CREATE TABLE test4(a int, b int GENERATED ALWAYS AS (a + 1), c text);
+INSERT INTO test4(a,c) VALUES (10,11), (10,11);
+CREATE INDEX test4_b_idx ON test4 USING btree (b);
+CREATE INDEX test4_a_1_idx ON test4 USING btree ((a+1));
+--expect return zero row
+SELECT * FROM bt_page_items('test4_b_idx', 1)
+EXCEPT ALL
+SELECT * FROM bt_page_items('test4_a_1_idx', 1);
+
 -- Failure when using a non-btree index.
 CREATE INDEX test1_a_hash ON test1 USING hash(a);
 SELECT bt_metap('test1_a_hash');

doc/src/sgml/catalogs.sgml

@@ -4589,6 +4589,21 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>indattrgenerated</structfield> <type>int2vector</type>
+       (references <link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link>.<structfield>attnum</structfield>)
+      </para>
+      <para>
+       This is an array of <structfield>indnatts</structfield> values that
+       indicate which virtual generated columns this index indexes.
+       For example, a value of <literal>1 3</literal> would mean that the first
+       and the third table columns of this index entries are virtual generated
+       column. A zero in this array indicates that the corresponding index
+       attribute is not virtual generated column reference.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
        <structfield>indexprs</structfield> <type>pg_node_tree</type>

src/backend/catalog/index.c

@@ -584,6 +584,12 @@ UpdateIndexRelation(Oid indexoid,
 	Relation	pg_index;
 	HeapTuple	tuple;
 	int			i;
+	int2vector *indgenkey;
+	int16	   *colgenerated;
+
+	colgenerated = palloc_array(int16, indexInfo->ii_NumIndexAttrs);
+	for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
+		colgenerated[i] = indexInfo->ii_IndexAttrGeneratedNumbers[i];
 
 	/*
 	 * Copy the index key, opclass, and indoption info into arrays (should we
@@ -595,6 +601,7 @@ UpdateIndexRelation(Oid indexoid,
 	indcollation = buildoidvector(collationOids, indexInfo->ii_NumIndexKeyAttrs);
 	indclass = buildoidvector(opclassOids, indexInfo->ii_NumIndexKeyAttrs);
 	indoption = buildint2vector(coloptions, indexInfo->ii_NumIndexKeyAttrs);
+	indgenkey = buildint2vector(colgenerated, indexInfo->ii_NumIndexAttrs);
 
 	/*
 	 * Convert the index expressions (if any) to a text datum
@@ -653,6 +660,7 @@ UpdateIndexRelation(Oid indexoid,
 	values[Anum_pg_index_indcollation - 1] = PointerGetDatum(indcollation);
 	values[Anum_pg_index_indclass - 1] = PointerGetDatum(indclass);
 	values[Anum_pg_index_indoption - 1] = PointerGetDatum(indoption);
+	values[Anum_pg_index_indattrgenerated - 1] = PointerGetDatum(indgenkey);
 	values[Anum_pg_index_indexprs - 1] = exprsDatum;
 	if (exprsDatum == (Datum) 0)
 		nulls[Anum_pg_index_indexprs - 1] = true;
@@ -1134,6 +1142,28 @@ index_create(Relation heapRelation,
 				}
 			}
 
+			/*
+			 * Internally, we convert index of virtual generation column into an
+			 * expression index. For example, if column 'b' is defined as (b INT
+			 * GENERATED ALWAYS AS (a * 2) VIRTUAL) then index over 'b' would
+			 * transformed into an expression index as ((a * 2)). As a result,
+			 * the pg_depend refobjsubid does not retain the original attribute
+			 * number of the virtual generated column. But we need rebuild any
+			 * index that was build on virtual generated column. so we need auto
+			 * dependencies on referenced virtual generated columns.
+			*/
+			for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
+			{
+				if (indexInfo->ii_IndexAttrGeneratedNumbers[i] != 0)
+				{
+					ObjectAddressSubSet(referenced, RelationRelationId,
+										heapRelationId,
+										indexInfo->ii_IndexAttrGeneratedNumbers[i]);
+					add_exact_object_address(&referenced, addrs);
+					have_simple_col = false;
+				}
+			}
+
 			/*
 			 * If there are no simply-referenced columns, give the index an
 			 * auto dependency on the whole table.  In most cases, this will
@@ -1411,6 +1441,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 
 		indexColNames = lappend(indexColNames, NameStr(att->attname));
 		newInfo->ii_IndexAttrNumbers[i] = oldInfo->ii_IndexAttrNumbers[i];
+		newInfo->ii_IndexAttrGeneratedNumbers[i] = oldInfo->ii_IndexAttrGeneratedNumbers[i];
 	}
 
 	/* Extract opclass options for each attribute */
@@ -2428,9 +2459,12 @@ IndexInfo *
 BuildIndexInfo(Relation index)
 {
 	IndexInfo  *ii;
+	HeapTuple	ht_idx;
 	Form_pg_index indexStruct = index->rd_index;
 	int			i;
 	int			numAtts;
+	Datum		indgenkeyDatum;
+	int2vector *indgenkey;
 
 	/* check the number of keys, and copy attr numbers into the IndexInfo */
 	numAtts = indexStruct->indnatts;
@@ -2454,9 +2488,19 @@ BuildIndexInfo(Relation index)
 					   index->rd_indam->amsummarizing,
 					   indexStruct->indisexclusion && indexStruct->indisunique);
 
+	ht_idx = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexStruct->indexrelid));
+	indgenkeyDatum = SysCacheGetAttrNotNull(INDEXRELID, ht_idx,
+											Anum_pg_index_indattrgenerated);
+	indgenkey = (int2vector *) DatumGetPointer(indgenkeyDatum);
+
 	/* fill in attribute numbers */
 	for (i = 0; i < numAtts; i++)
+	{
 		ii->ii_IndexAttrNumbers[i] = indexStruct->indkey.values[i];
+		ii->ii_IndexAttrGeneratedNumbers[i] = indgenkey->values[i];
+	}
+
+	ReleaseSysCache(ht_idx);
 
 	/* fetch exclusion constraint info if any */
 	if (indexStruct->indisexclusion)
@@ -2518,11 +2562,35 @@ BuildDummyIndexInfo(Relation index)
 	for (i = 0; i < numAtts; i++)
 		ii->ii_IndexAttrNumbers[i] = indexStruct->indkey.values[i];
 
+	/*
+	 * Index expressions or predicates are skipped here, see above comments. If
+	 * virtual generated columns references another column, ii_IndexAttrNumbers
+	 * will set to that referenced column. So do nothing for
+	 * ii_IndexAttrGeneratedNumbers here.
+	*/
+
 	/* We ignore the exclusion constraint if any */
 
 	return ii;
 }
 
+/*
+ * IndexOverVirtualGenerated
+ *		Return whether this index was built on virtual generated column.
+ */
+bool
+IsIndexOverVirtualGenerated(const IndexInfo *info)
+{
+	int			i;
+
+	for (i = 0; i < info->ii_NumIndexAttrs; i++)
+	{
+		if (AttributeNumberIsValid(info->ii_IndexAttrGeneratedNumbers[i]))
+			return true;
+	}
+	return false;
+}
+
 /*
  * CompareIndexInfo
  *		Return whether the properties of two indexes (in different tables)
@@ -2585,6 +2653,15 @@ CompareIndexInfo(const IndexInfo *info1, const IndexInfo *info2,
 				return false;
 		}
 
+		if (AttributeNumberIsValid(info1->ii_IndexAttrGeneratedNumbers[i]) ||
+			AttributeNumberIsValid(info2->ii_IndexAttrGeneratedNumbers[i]))
+		{
+			/* fail if index over virtual generated column does not match */
+			if (attmap->attnums[info2->ii_IndexAttrGeneratedNumbers[i] - 1] !=
+				info1->ii_IndexAttrGeneratedNumbers[i])
+				return false;
+		}
+
 		/* collation and opfamily are not valid for included columns */
 		if (i >= info1->ii_NumIndexKeyAttrs)
 			continue;