Function indexJoinPathTmpInit

pkg/planner/core/index_join_path.go:485–514

Reset the 'curIdxOff2KeyOff', 'curNotUsedIndexCols' and 'curNotUsedColLens' by innerKeys and idxCols * For each idxCols, If column can be found in innerKeys save offset of innerKeys in 'curIdxOff2KeyOff' Else, save -1 in 'curIdxOff2KeyOff' */ For example, innerKeys[t1.a, t1.sum_b, t1.c], idxCo

(
	sctx planctx.PlanContext,
	indexJoinInfo *indexJoinPathInfo,
	idxCols []*expression.Column,
	colLens []int)

// For example, innerKeys[t1.a, t1.sum_b, t1.c], idxCols [a, b, c]
// 'curIdxOff2KeyOff' = [0, -1, 2]
func indexJoinPathTmpInit(
	sctx planctx.PlanContext,
	indexJoinInfo *indexJoinPathInfo,
	idxCols []*expression.Column,
	colLens []int) *indexJoinPathTmp {
	tmpSchema := expression.NewSchema(indexJoinInfo.innerJoinKeys...)
	buildTmp := new(indexJoinPathTmp)
	buildTmp.curIdxOff2KeyOff = make([]int, len(idxCols))
	buildTmp.curNotUsedIndexCols = make([]*expression.Column, 0, len(idxCols))
	buildTmp.curNotUsedColLens = make([]int, 0, len(idxCols))
	for i, idxCol := range idxCols {
		buildTmp.curIdxOff2KeyOff[i] = tmpSchema.ColumnIndex(idxCol)
		if buildTmp.curIdxOff2KeyOff[i] >= 0 {
			// Don't use the join columns if their collations are unmatched and the new collation is enabled.
			if collate.NewCollationEnabled() && types.IsString(idxCol.RetType.GetType()) && types.IsString(indexJoinInfo.outerJoinKeys[buildTmp.curIdxOff2KeyOff[i]].RetType.GetType()) {
				et, err := expression.CheckAndDeriveCollationFromExprs(sctx.GetExprCtx(), "equal", types.ETInt, idxCol, indexJoinInfo.outerJoinKeys[buildTmp.curIdxOff2KeyOff[i]])
				if err != nil {
					logutil.BgLogger().Error("Unexpected error happened during constructing index join", zap.Stack("stack"))
				}
				if !collate.CompatibleCollate(idxCol.GetStaticType().GetCollate(), et.Collation) {
					buildTmp.curIdxOff2KeyOff[i] = -1
				}
			}
			continue
		}
		buildTmp.curNotUsedIndexCols = append(buildTmp.curNotUsedIndexCols, idxCol)
		buildTmp.curNotUsedColLens = append(buildTmp.curNotUsedColLens, colLens[i])
	}
	return buildTmp
}

// indexJoinPathFindUsefulEQIn analyzes the PushedDownConds held by inner child and split them to three parts.
// usefulEqOrInFilters is the continuous eq/in conditions on current unused index columns.