sql: support ALTER INDEX ... VISIBILITY ...

This commit adds support to `ALTER INDEX ... VISIBILITY ...`. `Visibility` is
currently not supported with `CREATE INDEX` or `CREATE TABLE`. Users would need
to create the index as it is fully not visible or fully visible first. And they
can change the index visibility to any float [0.0, 1.0] using `ALTER INDEX ...
VISIBILITY ...` Invisibility specifies the invisibility of an index to the
optimizer and can be any float64 between [0.0, 1.0]. An index with invisibility
0.0 means that the index is visible. An index with invisibility 1.0 means that
the index is fully not visible. By default, an index should be visible or
invisibility 0.0. An index with invisibility 1.0 is ignored by the optimizer
unless it is used for constraint check or is explicitly selected with index
hinting. An index with invisibility between (0.0, 1.0) would be made fully not
visible to a corresponding fraction of the queries. By convention, we will
refer any indexes with invisibility == 0.0 as visible, any indexes with
invisibility == 1.0 as fully not visible, and any indexes with index visibility
in-between as partially not visible.

Informs cockroachdb#82363

Release note (sql change): `ALTER INDEX ... VISIBILITY ...` is now supported.
It can change an index visibility to any visibility within [0.0, 1.0].
Visibility 0.0 means the index is not visible to the optimizer, while
visibility 1.0 means the index is fully visible. A value in the range
(0.0, 1.0) means the index will be visibile to the corresponding fraction of
queries.

Co-authored-by: Rebecca Taft <[email protected]>

docs/generated/sql/bnf/alter_index.bnf

@@ -32,12 +32,16 @@ alter_index_stmt ::=
 	| 'ALTER' 'INDEX' table_name '@' index_name 'NOT' 'VISIBLE'
 	| 'ALTER' 'INDEX' table_name '@' index_name 'INVISIBLE'
 	| 'ALTER' 'INDEX' table_name '@' index_name 'VISIBLE'
+	| 'ALTER' 'INDEX' table_name '@' index_name 'VISIBILITY' 'FCONST'
 	| 'ALTER' 'INDEX' index_name 'NOT' 'VISIBLE'
 	| 'ALTER' 'INDEX' index_name 'INVISIBLE'
 	| 'ALTER' 'INDEX' index_name 'VISIBLE'
+	| 'ALTER' 'INDEX' index_name 'VISIBILITY' 'FCONST'
 	| 'ALTER' 'INDEX' 'IF' 'EXISTS' table_name '@' index_name 'NOT' 'VISIBLE'
 	| 'ALTER' 'INDEX' 'IF' 'EXISTS' table_name '@' index_name 'INVISIBLE'
 	| 'ALTER' 'INDEX' 'IF' 'EXISTS' table_name '@' index_name 'VISIBLE'
+	| 'ALTER' 'INDEX' 'IF' 'EXISTS' table_name '@' index_name 'VISIBILITY' 'FCONST'
 	| 'ALTER' 'INDEX' 'IF' 'EXISTS' index_name 'NOT' 'VISIBLE'
 	| 'ALTER' 'INDEX' 'IF' 'EXISTS' index_name 'INVISIBLE'
 	| 'ALTER' 'INDEX' 'IF' 'EXISTS' index_name 'VISIBLE'
+	| 'ALTER' 'INDEX' 'IF' 'EXISTS' index_name 'VISIBILITY' 'FCONST'

docs/generated/sql/bnf/stmt_block.bnf

@@ -1453,6 +1453,7 @@ unreserved_keyword ::=
 	| 'VIEWCLUSTERSETTING'
 	| 'VIEWDEBUG'
 	| 'VISIBLE'
+	| 'VISIBILITY'
 	| 'VOLATILE'
 	| 'VOTERS'
 	| 'WITHIN'
@@ -2887,6 +2888,7 @@ alter_index_visible ::=
 	'NOT' 'VISIBLE'
 	| 'INVISIBLE'
 	| 'VISIBLE'
+	| 'VISIBILITY' 'FCONST'
 
 sequence_option_list ::=
 	( sequence_option_elem ) ( ( sequence_option_elem ) )*
@@ -4023,6 +4025,7 @@ bare_label_keywords ::=
 	| 'VIEWDEBUG'
 	| 'VIRTUAL'
 	| 'VISIBLE'
+	| 'VISIBILITY'
 	| 'VOLATILE'
 	| 'VOTERS'
 	| 'WHEN'

pkg/sql/opt/exec/execbuilder/testdata/not_visible_index

@@ -1406,7 +1406,8 @@ vectorized: true
   spans: [/2 - /2]
 
 statement ok
-DROP TABLE t
+DROP TABLE t;
+RESET optimizer_use_not_visible_indexes
 
 ############################################################################
 # We should log notices when dropping an invisible index might be different from marking an index invisible.
@@ -1528,8 +1529,13 @@ statement ok
 CREATE INDEX k_idx on t(k) INVISIBLE
 
 statement ok
-CREATE INDEX v_idx on t(k);
-ALTER INDEX v_idx INVISIBLE
+CREATE INDEX k1_idx on t(k);
+ALTER INDEX k1_idx INVISIBLE
+
+# Create an index with partial visibility.
+statement ok
+CREATE INDEX v_idx on t(v);
+ALTER INDEX v_idx VISIBILITY 0.5
 
 query TTBITTTBBBF colnames
 SELECT * FROM [SHOW INDEX FROM t]
@@ -1541,5 +1547,50 @@ t           t_pkey      false       3             v            v           N/A
 t           p_idx       true        1             p            p           ASC        false    false     false    0
 t           k_idx       true        1             k            k           ASC        false    false     false    0
 t           k_idx       true        2             p            p           ASC        false    true      false    0
-t           v_idx       true        1             k            k           ASC        false    false     false    0
-t           v_idx       true        2             p            p           ASC        false    true      false    0
+t           k1_idx      true        1             k            k           ASC        false    false     false    0
+t           k1_idx      true        2             p            p           ASC        false    true      false    0
+t           v_idx       true        1             v            v           ASC        false    false     false    0.5
+t           v_idx       true        2             p            p           ASC        false    true      false    0.5
+
+# Depending on the random seed v_idx may or may not be visible.
+statement ok
+SET testing_optimizer_random_seed=6320964980407535655
+
+query T
+EXPLAIN SELECT * FROM t WHERE v = 'foo'
+----
+distribution: local
+vectorized: true
+·
+• index join
+│ table: t@t_pkey
+│
+└── • scan
+      missing stats
+      table: t@v_idx
+      spans: [/'foo' - /'foo']
+
+statement ok
+SET testing_optimizer_random_seed=3164997759865821235
+
+query T
+EXPLAIN SELECT * FROM t WHERE v = 'foo'
+----
+distribution: local
+vectorized: true
+·
+• filter
+│ filter: v = 'foo'
+│
+└── • scan
+      missing stats
+      table: t@t_pkey
+      spans: FULL SCAN
+
+statement ok
+RESET testing_optimizer_random_seed
+
+# When the seed is unset we'll use a non-deterministic random number
+# to determine the visibility. Just make sure this doesn't cause an error.
+statement ok
+SELECT * FROM t WHERE v = 'foo'

pkg/sql/opt/metadata.go

@@ -699,6 +699,7 @@ func (md *Metadata) DuplicateTable(
 		partialIndexPredicates:   partialIndexPredicates,
 		indexPartitionLocalities: tabMeta.indexPartitionLocalities,
 		checkConstraintsStats:    checkConstraintsStats,
+		notVisibleIndexMap:       tabMeta.notVisibleIndexMap,
 	}
 	md.tables = append(md.tables, newTabMeta)
 	regionConfig, ok := md.TableAnnotation(tabID, regionConfigAnnID).(*multiregion.RegionConfig)

pkg/sql/opt/table_meta.go

@@ -12,6 +12,7 @@ package opt
 
 import (
 	"context"
+	"math/rand"
 
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/catpb"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/descpb"
@@ -204,6 +205,47 @@ type TableMeta struct {
 
 	// anns annotates the table metadata with arbitrary data.
 	anns [maxTableAnnIDCount]interface{}
+
+	// notVisibleIndexMap stores information about index invisibility which maps
+	// from index ordinal to index invisibility.
+	notVisibleIndexMap map[cat.IndexOrdinal]bool
+}
+
+// IsIndexNotVisible returns true if the given index is not visible, and false
+// if it is fully visible. If the index is partially visible (i.e., it has a
+// value for invisibility in the range (0.0, 1.0)), IsIndexNotVisible randomly
+// chooses to make the index fully not visible (to this query) with probability
+// proportional to the invisibility setting for the index. Otherwise, the index
+// is fully visible (to this query). IsIndexNotVisible caches the result so that
+// it always returns the same value for a given index.
+func (tm *TableMeta) IsIndexNotVisible(indexOrd cat.IndexOrdinal, rng *rand.Rand) bool {
+	if tm.notVisibleIndexMap == nil {
+		tm.notVisibleIndexMap = make(map[cat.IndexOrdinal]bool)
+	}
+	if val, ok := tm.notVisibleIndexMap[indexOrd]; ok {
+		return val
+	}
+	// Otherwise, roll the dice to assign index visibility.
+	indexInvisibility := tm.Table.Index(indexOrd).GetInvisibility()
+
+	// If the index invisibility is 40%, we want to make this index invisible 40%
+	// of the time (invisible to 40% of the queries).
+	isNotVisible := false
+	if indexInvisibility == 1 {
+		isNotVisible = true
+	} else if indexInvisibility != 0 {
+		var r float64
+		if rng == nil {
+			r = rand.Float64()
+		} else {
+			r = rng.Float64()
+		}
+		if r <= indexInvisibility {
+			isNotVisible = true
+		}
+	}
+	tm.notVisibleIndexMap[indexOrd] = isNotVisible
+	return isNotVisible
 }
 
 // TableAnnotation returns the given annotation that is associated with the

pkg/sql/opt/xform/groupby_funcs.go

@@ -528,7 +528,7 @@ func (c *CustomFuncs) GenerateLimitedGroupByScans(
 	var iter scanIndexIter
 	var sb indexScanBuilder
 	sb.Init(c, sp.Table)
-	iter.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, sp, nil /* filters */, rejectPrimaryIndex|rejectInvertedIndexes)
+	iter.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, sp, nil /* filters */, rejectPrimaryIndex|rejectInvertedIndexes)
 	iter.ForEach(func(index cat.Index, filters memo.FiltersExpr, indexCols opt.ColSet, isCovering bool, constProj memo.ProjectionsExpr) {
 		// The iterator only produces pseudo-partial indexes (the predicate is
 		// true) because no filters are passed to iter.Init to imply a partial

pkg/sql/opt/xform/join_funcs.go

@@ -408,7 +408,7 @@ func (c *CustomFuncs) generateLookupJoinsImpl(
 	var pkCols opt.ColList
 	var newScanPrivate *memo.ScanPrivate
 	var iter scanIndexIter
-	iter.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, scanPrivate, on, rejectInvertedIndexes)
+	iter.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, scanPrivate, on, rejectInvertedIndexes)
 	iter.ForEach(func(index cat.Index, onFilters memo.FiltersExpr, indexCols opt.ColSet, _ bool, _ memo.ProjectionsExpr) {
 		// Skip indexes that do not cover all virtual projection columns, if
 		// there are any. This can happen when there are multiple virtual
@@ -804,7 +804,7 @@ func (c *CustomFuncs) GenerateInvertedJoins(
 	var optionalFilters memo.FiltersExpr
 
 	var iter scanIndexIter
-	iter.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, scanPrivate, on, rejectNonInvertedIndexes)
+	iter.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, scanPrivate, on, rejectNonInvertedIndexes)
 	iter.ForEach(func(index cat.Index, onFilters memo.FiltersExpr, indexCols opt.ColSet, _ bool, _ memo.ProjectionsExpr) {
 		invertedJoin := memo.InvertedJoinExpr{Input: input}
 		numPrefixCols := index.NonInvertedPrefixColumnCount()

pkg/sql/opt/xform/limit_funcs.go

@@ -117,7 +117,7 @@ func (c *CustomFuncs) GenerateLimitedScans(
 	// Iterate over all non-inverted, non-partial indexes, looking for those
 	// that can be limited.
 	var iter scanIndexIter
-	iter.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, scanPrivate, nil /* filters */, rejectInvertedIndexes|rejectPartialIndexes)
+	iter.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, scanPrivate, nil /* filters */, rejectInvertedIndexes|rejectPartialIndexes)
 	iter.ForEach(func(index cat.Index, filters memo.FiltersExpr, indexCols opt.ColSet, isCovering bool, constProj memo.ProjectionsExpr) {
 		// The iterator rejects partial indexes because there are no filters to
 		// imply a partial index predicate. constProj is a projection of
@@ -286,7 +286,7 @@ func (c *CustomFuncs) GenerateLimitedTopKScans(
 	var iter scanIndexIter
 	var sb indexScanBuilder
 	sb.Init(c, sp.Table)
-	iter.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, sp, nil /* filters */, rejectPrimaryIndex|rejectInvertedIndexes)
+	iter.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, sp, nil /* filters */, rejectPrimaryIndex|rejectInvertedIndexes)
 	iter.ForEach(func(index cat.Index, filters memo.FiltersExpr, indexCols opt.ColSet, isCovering bool, constProj memo.ProjectionsExpr) {
 		// The iterator only produces pseudo-partial indexes (the predicate is
 		// true) because no filters are passed to iter.Init to imply a partial

pkg/sql/opt/xform/optimizer.go

@@ -98,7 +98,8 @@ type Optimizer struct {
 	// JoinOrderBuilder adds new join orderings to the memo.
 	jb JoinOrderBuilder
 
-	// rng is used to deterministically perturb costs and/or disable rules.
+	// rng is used to deterministically perturb costs and/or disable rules and/or
+	// determine the visibility (for this query) of a partially visible index.
 	rng *rand.Rand
 
 	// scratchSort is used to avoid repeated allocations during sort enforcement.

pkg/sql/opt/xform/scan_funcs.go

@@ -47,7 +47,7 @@ func (c *CustomFuncs) GenerateIndexScans(
 	// Iterate over all non-inverted and non-partial secondary indexes.
 	var pkCols opt.ColSet
 	var iter scanIndexIter
-	iter.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, scanPrivate, nil /* filters */, rejectPrimaryIndex|rejectInvertedIndexes)
+	iter.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, scanPrivate, nil /* filters */, rejectPrimaryIndex|rejectInvertedIndexes)
 	iter.ForEach(func(index cat.Index, filters memo.FiltersExpr, indexCols opt.ColSet, isCovering bool, constProj memo.ProjectionsExpr) {
 		// The iterator only produces pseudo-partial indexes (the predicate is
 		// true) because no filters are passed to iter.Init to imply a partial

pkg/sql/opt/xform/scan_index_iter.go

@@ -15,7 +15,6 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/opt"
 	"github.com/cockroachdb/cockroach/pkg/sql/opt/cat"
 	"github.com/cockroachdb/cockroach/pkg/sql/opt/memo"
-	"github.com/cockroachdb/cockroach/pkg/sql/opt/norm"
 	"github.com/cockroachdb/cockroach/pkg/sql/opt/partialidx"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/eval"
 	"github.com/cockroachdb/errors"
@@ -51,7 +50,7 @@ const (
 // of a Scan operator table.
 type scanIndexIter struct {
 	evalCtx *eval.Context
-	f       *norm.Factory
+	e       *explorer
 	im      *partialidx.Implicator
 	tabMeta *opt.TableMeta
 
@@ -86,7 +85,7 @@ type scanIndexIter struct {
 // Init initializes a new scanIndexIter.
 func (it *scanIndexIter) Init(
 	evalCtx *eval.Context,
-	f *norm.Factory,
+	e *explorer,
 	mem *memo.Memo,
 	im *partialidx.Implicator,
 	scanPrivate *memo.ScanPrivate,
@@ -97,7 +96,7 @@ func (it *scanIndexIter) Init(
 	// reused. Field reuse must be explicit.
 	*it = scanIndexIter{
 		evalCtx:     evalCtx,
-		f:           f,
+		e:           e,
 		im:          im,
 		tabMeta:     mem.Metadata().TableMeta(scanPrivate.Table),
 		scanPrivate: scanPrivate,
@@ -227,7 +226,7 @@ func (it *scanIndexIter) ForEachStartingAfter(ord int, f enumerateIndexFunc) {
 		} else {
 			// If we are not forcing any specific index and not visible index feature is
 			// enabled here, ignore not visible indexes.
-			if (index.GetInvisibility() != 0.0) && !it.scanPrivate.Flags.DisableNotVisibleIndex &&
+			if it.tabMeta.IsIndexNotVisible(ord, it.e.o.rng) && !it.scanPrivate.Flags.DisableNotVisibleIndex &&
 				!it.evalCtx.SessionData().OptimizerUseNotVisibleIndexes {
 				continue
 			}
@@ -374,9 +373,9 @@ func (it *scanIndexIter) buildConstProjectionsFromPredicate(
 			panic(errors.AssertionFailedf("could not extract constant value for column %d", col))
 		}
 
-		scalar := it.f.ConstructConstVal(val, typ)
+		scalar := it.e.f.ConstructConstVal(val, typ)
 
-		proj = append(proj, it.f.ConstructProjectionsItem(
+		proj = append(proj, it.e.f.ConstructProjectionsItem(
 			scalar,
 			col,
 		))

pkg/sql/opt/xform/select_funcs.go

@@ -106,7 +106,7 @@ func (c *CustomFuncs) GeneratePartialIndexScans(
 	// Iterate over all partial indexes.
 	var pkCols opt.ColSet
 	var iter scanIndexIter
-	iter.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, scanPrivate, filters, rejectNonPartialIndexes|rejectInvertedIndexes)
+	iter.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, scanPrivate, filters, rejectNonPartialIndexes|rejectInvertedIndexes)
 	iter.ForEach(func(index cat.Index, remainingFilters memo.FiltersExpr, indexCols opt.ColSet, isCovering bool, constProj memo.ProjectionsExpr) {
 		var sb indexScanBuilder
 		sb.Init(c, scanPrivate.Table)
@@ -437,7 +437,7 @@ func (c *CustomFuncs) GenerateConstrainedScans(
 
 	// Iterate over all non-inverted indexes.
 	var iter scanIndexIter
-	iter.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, scanPrivate, explicitFilters, rejectInvertedIndexes)
+	iter.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, scanPrivate, explicitFilters, rejectInvertedIndexes)
 	iter.ForEach(func(index cat.Index, filters memo.FiltersExpr, indexCols opt.ColSet, isCovering bool, constProj memo.ProjectionsExpr) {
 
 		// Create a prefix sorter that describes which index partitions are
@@ -881,7 +881,7 @@ func (c *CustomFuncs) GenerateInvertedIndexScans(
 
 	// Iterate over all inverted indexes.
 	var iter scanIndexIter
-	iter.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, scanPrivate, filters, rejectNonInvertedIndexes)
+	iter.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, scanPrivate, filters, rejectNonInvertedIndexes)
 	iter.ForEach(func(index cat.Index, filters memo.FiltersExpr, indexCols opt.ColSet, _ bool, _ memo.ProjectionsExpr) {
 		// Check whether the filter can constrain the index.
 		spanExpr, constraint, remainingFilters, pfState, ok := invertedidx.TryFilterInvertedIndex(
@@ -1112,7 +1112,7 @@ func (c *CustomFuncs) GenerateZigzagJoins(
 	// TODO(mgartner): We should consider primary indexes when it has multiple
 	// columns and only the first is being constrained.
 	var iter scanIndexIter
-	iter.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, scanPrivate, filters, rejectPrimaryIndex|rejectInvertedIndexes)
+	iter.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, scanPrivate, filters, rejectPrimaryIndex|rejectInvertedIndexes)
 	iter.ForEach(func(leftIndex cat.Index, outerFilters memo.FiltersExpr, leftCols opt.ColSet, _ bool, _ memo.ProjectionsExpr) {
 		leftFixed := c.indexConstrainedCols(leftIndex, scanPrivate.Table, fixedCols)
 		// Short-circuit quickly if the first column in the index is not a fixed
@@ -1122,7 +1122,7 @@ func (c *CustomFuncs) GenerateZigzagJoins(
 		}
 
 		var iter2 scanIndexIter
-		iter2.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, scanPrivate, outerFilters, rejectPrimaryIndex|rejectInvertedIndexes)
+		iter2.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, scanPrivate, outerFilters, rejectPrimaryIndex|rejectInvertedIndexes)
 		iter2.SetOriginalFilters(filters)
 		iter2.ForEachStartingAfter(leftIndex.Ordinal(), func(rightIndex cat.Index, innerFilters memo.FiltersExpr, rightCols opt.ColSet, _ bool, _ memo.ProjectionsExpr) {
 			// Check if we have zigzag hints.
@@ -1451,7 +1451,7 @@ func (c *CustomFuncs) GenerateInvertedIndexZigzagJoins(
 
 	// Iterate over all inverted indexes.
 	var iter scanIndexIter
-	iter.Init(c.e.evalCtx, c.e.f, c.e.mem, &c.im, scanPrivate, filters, rejectNonInvertedIndexes)
+	iter.Init(c.e.evalCtx, c.e, c.e.mem, &c.im, scanPrivate, filters, rejectNonInvertedIndexes)
 	iter.ForEach(func(index cat.Index, filters memo.FiltersExpr, indexCols opt.ColSet, _ bool, _ memo.ProjectionsExpr) {
 		// Check if we have zigzag hints.
 		if !scanPrivate.Flags.ZigzagIndexes.Empty() && !scanPrivate.Flags.ZigzagIndexes.Contains(index.Ordinal()) {