colexec: reorder some fields to reduce memory footprint

This commit applies some of the fixes found by the `fieldalignment` tool
on the colexec packages which reorder some fields in the structs so that
the memory footprint is reduced.

Release note: None

pkg/sql/colexec/colexecargs/expr.go

@@ -33,8 +33,8 @@ func NewExprHelper() *ExprHelper {
 // ExprHelper is a utility struct that helps with expression handling in the
 // vectorized engine.
 type ExprHelper struct {
-	helper  execinfrapb.ExprHelper
 	SemaCtx *tree.SemaContext
+	helper  execinfrapb.ExprHelper
 }
 
 // ProcessExpr processes the given expression and returns a well-typed

pkg/sql/colexec/colexecbase/cast_tmpl.go

@@ -229,12 +229,11 @@ func IsCastSupported(fromType, toType *types.T) bool {
 }
 
 type castOpBase struct {
-	colexecop.OneInputInitCloserHelper
-
 	allocator *colmem.Allocator
+	evalCtx   *eval.Context
+	colexecop.OneInputInitCloserHelper
 	colIdx    int
 	outputIdx int
-	evalCtx   *eval.Context
 }
 
 func (c *castOpBase) Reset(ctx context.Context) {

pkg/sql/colexec/colexecbase/distinct_tmpl.go

@@ -139,6 +139,8 @@ func newPartitioner(t *types.T, nullsAreDistinct bool) partitioner {
 // true to the resultant bool column for every value that differs from the
 // previous one.
 type distinct_TYPEOp struct {
+	colexecop.OneInputHelper
+
 	// outputCol is the boolean output column. It is shared by all of the
 	// other distinct operators in a distinct operator set.
 	outputCol []bool
@@ -147,8 +149,6 @@ type distinct_TYPEOp struct {
 	// still works across batch boundaries.
 	lastVal _GOTYPE
 
-	colexecop.OneInputHelper
-
 	// distinctColIdx is the index of the column to distinct upon.
 	distinctColIdx int
 

pkg/sql/colexec/colexecbase/simple_project.go

@@ -22,11 +22,10 @@ import (
 // simpleProjectOp is an operator that implements "simple projection" - removal of
 // columns that aren't needed by later operators.
 type simpleProjectOp struct {
-	colexecop.OneInputInitCloserHelper
 	colexecop.NonExplainable
-
+	batches map[coldata.Batch]*projectingBatch
+	colexecop.OneInputInitCloserHelper
 	projection []uint32
-	batches    map[coldata.Batch]*projectingBatch
 	// numBatchesLoggingThreshold is the threshold on the number of items in
 	// 'batches' map at which we will log a message when a new projectingBatch
 	// is created. It is growing exponentially.