Merge #75595

75595: colexechash: introduce a type alias for keyID r=yuzefovich a=yuzefovich

Release note: None

Co-authored-by: Yahor Yuzefovich <[email protected]>

pkg/sql/colexec/colexechash/hashtable.go

@@ -62,6 +62,15 @@ const (
 	HashTableDeletingProbeMode
 )
 
+// keyID encodes the ordinal of the corresponding tuple.
+//
+// For each tuple with the ordinal 'i' (the ordinal among all tuples in the
+// hash table or within a single probing batch), keyID is calculated as:
+//   keyID = i + 1.
+//
+// keyID of 0 is reserved to indicate the end of the hash chain.
+type keyID = uint64
+
 // hashChains describes the partitioning of a set of tuples into singly-linked
 // lists ("buckets") where all tuples in a list have the same hash.
 //
@@ -70,25 +79,21 @@ const (
 // First[bucket], and the following keyIDs of the tuples in the list can be
 // found using Next[keyID] traversal. Whenever keyID of 0 is encountered, the
 // end of the list has been reached.
-//
-// For each tuple with the ordinal 'i' (the ordinal among all tuples in the
-// hash table or within a single probing batch), keyID is calculated as:
-//   keyID = i + 1.
 type hashChains struct {
 	// First stores the first keyID of the tuple that resides in each bucket.
 	// The tuple is the head of the corresponding hash chain.
 	//
 	// The length of this slice is equal to the number of buckets used in the
 	// hash table at the moment.
-	First []uint64
+	First []keyID
 
 	// Next is a densely-packed list that stores the keyID of the next tuple in
 	// the hash chain, where an ID of 0 is reserved to represent the end of the
 	// chain.
 	//
 	// The length of this slice is equal to the number of tuples stored in the
 	// hash table at the moment plus one (Next[0] is unused).
-	Next []uint64
+	Next []keyID
 }
 
 // hashTableProbeBuffer stores the information related to the probing batch.
@@ -146,7 +151,7 @@ type hashTableProbeBuffer struct {
 	//   ToCheckID[i] = Next[ToCheckID[i]].
 	// Whenever ToCheckID[i] becomes 0, there are no more matches for the ith
 	// probing tuple.
-	ToCheckID []uint64
+	ToCheckID []keyID
 
 	// differs stores whether the probing tuple included in ToCheck differs
 	// from the corresponding "candidate" tuple specified in ToCheckID.
@@ -186,7 +191,7 @@ type hashTableProbeBuffer struct {
 	// once the tuple is determined to not have duplicates with any tuples
 	// already in the hash table.
 	// See a comment on DistinctBuild for an example.
-	HeadID []uint64
+	HeadID []keyID
 
 	// HashBuffer stores the hash values of each tuple in the probing batch. It
 	// will be dynamically updated when the HashTable is built in distinct mode.
@@ -237,7 +242,7 @@ type HashTable struct {
 	// the hash table that has the same value as the current key. The HeadID of
 	// the key is the first key of that value found in the next linked list.
 	// This field will be lazily populated by the prober.
-	Same []uint64
+	Same []keyID
 	// Visited represents whether each of the corresponding keys have been
 	// touched by the prober.
 	Visited []bool
@@ -339,7 +344,7 @@ func NewHashTable(
 	ht := &HashTable{
 		allocator: allocator,
 		BuildScratch: hashChains{
-			First: make([]uint64, initialNumHashBuckets),
+			First: make([]keyID, initialNumHashBuckets),
 		},
 		Keys:              make([]coldata.Vec, len(keyCols)),
 		Vals:              colexecutils.NewAppendOnlyBufferedBatch(allocator, sourceTypes, colsToStore),
@@ -352,11 +357,11 @@ func NewHashTable(
 	}
 
 	if buildMode == HashTableDistinctBuildMode {
-		ht.ProbeScratch.First = make([]uint64, initialNumHashBuckets)
+		ht.ProbeScratch.First = make([]keyID, initialNumHashBuckets)
 		// ht.BuildScratch.Next will be populated dynamically by appending to
 		// it, but we need to make sure that the special keyID=0 (which
 		// indicates the end of the hash chain) is always present.
-		ht.BuildScratch.Next = []uint64{0}
+		ht.BuildScratch.Next = []keyID{0}
 	}
 
 	ht.cancelChecker.Init(ctx)
@@ -596,7 +601,7 @@ func (ht *HashTable) ComputeHashAndBuildChains(batch coldata.Batch) {
 
 	batchLength := batch.Length()
 	if cap(ht.ProbeScratch.Next) < batchLength+1 {
-		ht.ProbeScratch.Next = make([]uint64, batchLength+1)
+		ht.ProbeScratch.Next = make([]keyID, batchLength+1)
 	}
 	ht.ComputeBuckets(ht.ProbeScratch.Next[1:batchLength+1], ht.Keys, batchLength, batch.Selection())
 	ht.ProbeScratch.HashBuffer = append(ht.ProbeScratch.HashBuffer[:0], ht.ProbeScratch.Next[1:batchLength+1]...)
@@ -630,7 +635,7 @@ func (ht *HashTable) ComputeHashAndBuildChains(batch coldata.Batch) {
 func (ht *HashTable) FindBuckets(
 	batch coldata.Batch,
 	keyCols []coldata.Vec,
-	first, next []uint64,
+	first, next []keyID,
 	duplicatesChecker func([]coldata.Vec, uint64, []int) uint64,
 ) {
 	batchLength := batch.Length()
@@ -662,7 +667,7 @@ func (ht *HashTable) FindBuckets(
 func (ht *HashTable) RemoveDuplicates(
 	batch coldata.Batch,
 	keyCols []coldata.Vec,
-	first, next []uint64,
+	first, next []keyID,
 	duplicatesChecker func([]coldata.Vec, uint64, []int) uint64,
 ) {
 	ht.FindBuckets(batch, keyCols, first, next, duplicatesChecker)
@@ -757,7 +762,7 @@ func (ht *HashTable) ComputeBuckets(buckets []uint64, keys []coldata.Vec, nKeys
 }
 
 // buildNextChains builds the hash map from the computed hash values.
-func (ht *HashTable) buildNextChains(first, next []uint64, offset, batchSize uint64) {
+func (ht *HashTable) buildNextChains(first, next []keyID, offset, batchSize uint64) {
 	// The loop direction here is reversed to ensure that when we are building the
 	// next chain for the probe table, the keyID in each equality chain inside
 	// `next` is strictly in ascending order. This is crucial to ensure that when
@@ -799,7 +804,7 @@ func (p *hashTableProbeBuffer) SetupLimitedSlices(length int, buildMode HashTabl
 	// Note that we don't use maybeAllocate* methods below because ToCheckID and
 	// ToCheck don't need to be zeroed out when reused.
 	if cap(p.ToCheckID) < length {
-		p.ToCheckID = make([]uint64, length)
+		p.ToCheckID = make([]keyID, length)
 	} else {
 		p.ToCheckID = p.ToCheckID[:length]
 	}
@@ -812,7 +817,7 @@ func (p *hashTableProbeBuffer) SetupLimitedSlices(length int, buildMode HashTabl
 
 // FindNext determines the id of the next key inside the ToCheckID buckets for
 // each equality column key in ToCheck.
-func (ht *HashTable) FindNext(next []uint64, nToCheck uint64) {
+func (ht *HashTable) FindNext(next []keyID, nToCheck uint64) {
 	for _, toCheck := range ht.ProbeScratch.ToCheck[:nToCheck] {
 		ht.ProbeScratch.ToCheckID[toCheck] = next[ht.ProbeScratch.ToCheckID[toCheck]]
 	}