func makeIsNotNull(left parser.TypedExpr) parser.TypedExpr {
return parser.NewTypedComparisonExpr(
parser.IsNot,
left,
parser.DNull,
)
}
func simplifyNotExpr(n *parser.NotExpr) (parser.TypedExpr, bool) {
switch t := n.Expr.(type) {
case *parser.ComparisonExpr:
op := t.Operator
switch op {
case parser.EQ:
op = parser.NE
case parser.NE:
op = parser.EQ
case parser.GT:
op = parser.LE
case parser.GE:
op = parser.LT
case parser.LT:
op = parser.GE
case parser.LE:
op = parser.GT
case parser.In:
op = parser.NotIn
case parser.NotIn:
op = parser.In
case parser.Like:
op = parser.NotLike
case parser.NotLike:
op = parser.Like
case parser.SimilarTo:
op = parser.NotSimilarTo
case parser.NotSimilarTo:
op = parser.SimilarTo
default:
return parser.MakeDBool(true), false
}
return simplifyExpr(parser.NewTypedComparisonExpr(
op,
t.TypedLeft(),
t.TypedRight(),
))
case *parser.AndExpr:
// De Morgan's Law: NOT (a AND b) -> (NOT a) OR (NOT b)
return simplifyExpr(parser.NewTypedOrExpr(
parser.NewTypedNotExpr(t.TypedLeft()),
parser.NewTypedNotExpr(t.TypedRight()),
))
case *parser.OrExpr:
// De Morgan's Law: NOT (a OR b) -> (NOT a) AND (NOT b)
return simplifyExpr(parser.NewTypedAndExpr(
parser.NewTypedNotExpr(t.TypedLeft()),
parser.NewTypedNotExpr(t.TypedRight()),
))
}
return parser.MakeDBool(true), false
}
func makePrefixRange(prefix parser.DString, datum parser.TypedExpr, complete bool) parser.TypedExpr {
if complete {
return parser.NewTypedComparisonExpr(
parser.EQ,
datum,
&prefix,
)
}
if len(prefix) == 0 {
return parser.MakeDBool(true)
}
return parser.NewTypedAndExpr(
parser.NewTypedComparisonExpr(
parser.GE,
datum,
&prefix,
),
parser.NewTypedComparisonExpr(
parser.LT,
datum,
parser.NewDString(string(roachpb.Key(prefix).PrefixEnd())),
),
)
}
func simplifyOneOrExpr(left, right parser.TypedExpr) (parser.TypedExpr, parser.TypedExpr, bool) {
lcmp, ok := left.(*parser.ComparisonExpr)
if !ok {
return left, right, true
}
rcmp, ok := right.(*parser.ComparisonExpr)
if !ok {
return left, right, true
}
lcmpLeft, lcmpRight := lcmp.TypedLeft(), lcmp.TypedRight()
rcmpLeft, rcmpRight := rcmp.TypedLeft(), rcmp.TypedRight()
if !isDatum(lcmpRight) || !isDatum(rcmpRight) {
return parser.MakeDBool(true), nil, false
}
if !varEqual(lcmpLeft, rcmpLeft) {
return left, right, true
}
if lcmp.Operator == parser.IsNot || rcmp.Operator == parser.IsNot {
switch lcmp.Operator {
case parser.Is:
if lcmpRight == parser.DNull && rcmpRight == parser.DNull {
// a IS NULL OR a IS NOT NULL
return parser.MakeDBool(true), nil, true
}
case parser.IsNot:
if lcmpRight == parser.DNull {
switch rcmp.Operator {
case parser.Is:
if rcmpRight == parser.DNull {
// a IS NOT NULL OR a IS NULL
return parser.MakeDBool(true), nil, true
}
case parser.IsNot:
if rcmpRight == parser.DNull {
// a IS NOT NULL OR a IS NOT NULL
return left, nil, true
}
}
}
}
return left, right, true
}
if lcmp.Operator == parser.In || rcmp.Operator == parser.In {
left, right = simplifyOneOrInExpr(lcmp, rcmp)
return left, right, true
}
if reflect.TypeOf(lcmpRight) != reflect.TypeOf(rcmpRight) {
allowCmp := false
switch lcmp.Operator {
case parser.EQ, parser.NE, parser.GT, parser.GE, parser.LT, parser.LE:
switch rcmp.Operator {
case parser.EQ, parser.NE, parser.GT, parser.GE, parser.LT, parser.LE:
// Break, permitting heterogeneous comparison.
allowCmp = true
}
}
if !allowCmp {
// If the types of the left and right datums are different, no
// simplification is possible.
return left, right, true
}
}
ldatum := lcmpRight.(parser.Datum)
rdatum := rcmpRight.(parser.Datum)
cmp := ldatum.Compare(rdatum)
// Determine which expression to use when either expression (left or right)
// is valid as a return value but their types are different. The reason
// to prefer a comparison between a column value and a datum of the same
// type is that it makes index constraint construction easier.
either := lcmp
if !ldatum.TypeEqual(rdatum) {
switch ta := lcmpLeft.(type) {
case *qvalue:
if ta.datum.TypeEqual(rdatum) {
either = rcmp
}
}
}
// TODO(pmattis): Figure out how to generate this logic.
switch lcmp.Operator {
case parser.EQ:
switch rcmp.Operator {
case parser.EQ:
// a = x OR a = y
if cmp == 0 {
// x = y
return either, nil, true
} else if cmp == 1 {
// x > y
ldatum, rdatum = rdatum, ldatum
}
return parser.NewTypedComparisonExpr(
parser.In,
lcmpLeft,
&parser.DTuple{ldatum, rdatum},
), nil, true
case parser.NE:
// a = x OR a != y
if cmp == 0 {
// x = y
return makeIsNotNull(lcmpLeft), nil, true
}
return right, nil, true
case parser.GT:
// a = x OR a > y
if cmp == 1 {
// x > y OR x = y
return right, nil, true
} else if cmp == 0 {
return parser.NewTypedComparisonExpr(
parser.GE,
lcmpLeft,
either.TypedRight(),
), nil, true
}
return left, right, true
case parser.GE:
// a = x OR a >= y
if cmp != -1 {
// x >= y
return right, nil, true
}
return left, right, true
case parser.LT:
// a = x OR a < y
if cmp == -1 {
// x < y OR x = y
return right, nil, true
} else if cmp == 0 {
return parser.NewTypedComparisonExpr(
parser.LE,
lcmpLeft,
either.TypedRight(),
), nil, true
}
return left, right, true
case parser.LE:
// a = x OR a <= y
if cmp != 1 {
// x <= y
return right, nil, true
}
return left, right, true
}
case parser.NE:
switch rcmp.Operator {
case parser.EQ:
// a != x OR a = y
if cmp == 0 {
// x = y
return makeIsNotNull(lcmpLeft), nil, true
}
// x != y
return left, nil, true
case parser.NE:
// a != x OR a != y
if cmp == 0 {
// x = y
return either, nil, true
}
// x != y
return makeIsNotNull(lcmpLeft), nil, true
case parser.GT:
// a != x OR a > y
if cmp == 1 {
// x > y
return makeIsNotNull(lcmpLeft), nil, true
}
// x <= y
return left, nil, true
case parser.GE:
// a != x OR a >= y
if cmp != -1 {
// x >= y
return makeIsNotNull(lcmpLeft), nil, true
}
// x < y
return left, nil, true
case parser.LT:
// a != x OR a < y
if cmp == -1 {
// x < y
return makeIsNotNull(lcmpLeft), nil, true
}
// x >= y
return left, nil, true
case parser.LE:
// a != x OR a <= y
if cmp != 1 {
// x <= y
return makeIsNotNull(lcmpLeft), nil, true
}
// x > y
return left, nil, true
}
case parser.GT:
switch rcmp.Operator {
case parser.EQ:
// a > x OR a = y
if cmp == -1 {
// x < y
return left, nil, true
} else if cmp == 0 {
return parser.NewTypedComparisonExpr(
parser.GE,
lcmpLeft,
either.TypedRight(),
), nil, true
}
// x > y
return left, right, true
case parser.NE:
// a > x OR a != y
if cmp == -1 {
// x < y
return makeIsNotNull(lcmpLeft), nil, true
}
// x >= y
return right, nil, true
case parser.GT, parser.GE:
// a > x OR (a > y OR a >= y)
if cmp == -1 {
return left, nil, true
}
return right, nil, true
case parser.LT:
// a > x OR a < y
if cmp == 0 {
// x = y
return parser.NewTypedComparisonExpr(
parser.NE,
lcmpLeft,
either.TypedRight(),
), nil, true
} else if cmp == -1 {
return makeIsNotNull(lcmpLeft), nil, true
}
// x != y
return left, right, true
case parser.LE:
// a > x OR a <= y
if cmp != 1 {
// x = y
return makeIsNotNull(lcmpLeft), nil, true
}
// x != y
return left, right, true
}
case parser.GE:
switch rcmp.Operator {
case parser.EQ:
// a >= x OR a = y
if cmp != 1 {
// x >. y
return left, nil, true
}
// x < y
return left, right, true
case parser.NE:
// a >= x OR a != y
if cmp != 1 {
// x <= y
return makeIsNotNull(lcmpLeft), nil, true
}
// x > y
return right, nil, true
case parser.GT:
// a >= x OR a > y
if cmp != 1 {
// x <= y
return left, nil, true
}
// x > y
return right, nil, true
case parser.GE:
// a >= x OR a >= y
if cmp == -1 {
// x < y
return left, nil, true
}
// x >= y
return right, nil, true
case parser.LT, parser.LE:
// a >= x OR a < y
if cmp != 1 {
// x <= y
return makeIsNotNull(lcmpLeft), nil, true
}
// x > y
return left, right, true
}
case parser.LT:
switch rcmp.Operator {
case parser.EQ:
// a < x OR a = y
if cmp == 0 {
// x = y
return parser.NewTypedComparisonExpr(
parser.LE,
lcmpLeft,
either.TypedRight(),
), nil, true
} else if cmp == 1 {
// x > y
return left, nil, true
}
// x < y
return left, right, true
case parser.NE:
// a < x OR a != y
if cmp == 1 {
return makeIsNotNull(lcmpLeft), nil, true
}
return right, nil, true
case parser.GT:
// a < x OR a > y
if cmp == 0 {
// x = y
return parser.NewTypedComparisonExpr(
parser.NE,
lcmpLeft,
either.TypedRight(),
), nil, true
} else if cmp == 1 {
// x > y
return makeIsNotNull(lcmpLeft), nil, true
}
return left, right, true
case parser.GE:
// a < x OR a >= y
if cmp == -1 {
// x < y
return left, right, true
}
// x >= y
return makeIsNotNull(lcmpLeft), nil, true
case parser.LT, parser.LE:
// a < x OR (a < y OR a <= y)
if cmp == 1 {
// x > y
return left, nil, true
}
// x < y
return right, nil, true
}
case parser.LE:
switch rcmp.Operator {
case parser.EQ:
// a <= x OR a = y
if cmp == -1 {
// x < y
return left, right, true
}
// x >= y
return left, nil, true
case parser.NE:
// a <= x OR a != y
if cmp != -1 {
// x >= y
return makeIsNotNull(lcmpLeft), nil, true
}
// x < y
return right, nil, true
case parser.GT, parser.GE:
// a <= x OR (a > y OR a >= y)
if cmp != -1 {
// x >= y
return makeIsNotNull(lcmpLeft), nil, true
}
// x < y
return left, right, true
case parser.LT, parser.LE:
// a <= x OR a < y
if cmp == -1 {
// x < y
return right, nil, true
}
// x >= y
return left, nil, true
}
case parser.Is:
switch rcmp.Operator {
case parser.Is:
if lcmpRight == parser.DNull && rcmpRight == parser.DNull {
// a IS NULL OR a IS NULL
return left, nil, true
}
}
}
return parser.MakeDBool(true), nil, false
}
func simplifyOneAndInExpr(left, right *parser.ComparisonExpr) (parser.TypedExpr, parser.TypedExpr) {
if left.Operator != parser.In && right.Operator != parser.In {
panic(fmt.Sprintf("IN expression required: %s vs %s", left, right))
}
origLeft, origRight := left, right
switch left.Operator {
case parser.EQ, parser.NE, parser.GT, parser.GE, parser.LT, parser.LE, parser.Is:
switch right.Operator {
case parser.In:
left, right = right, left
}
fallthrough
case parser.In:
ltuple := *left.Right.(*parser.DTuple)
switch right.Operator {
case parser.Is:
if right.Right == parser.DNull {
return parser.MakeDBool(false), nil
}
case parser.EQ, parser.NE, parser.GT, parser.GE, parser.LT, parser.LE:
// Our tuple will be sorted (see simplifyComparisonExpr). Binary search
// for the right datum.
datum := right.Right.(parser.Datum)
i := sort.Search(len(ltuple), func(i int) bool {
return ltuple[i].(parser.Datum).Compare(datum) >= 0
})
switch right.Operator {
case parser.EQ:
if i < len(ltuple) && ltuple[i].Compare(datum) == 0 {
return right, nil
}
return parser.MakeDBool(false), nil
case parser.NE:
if i < len(ltuple) && ltuple[i].Compare(datum) == 0 {
if len(ltuple) < 2 {
return parser.MakeDBool(false), nil
}
ltuple = remove(ltuple, i)
}
return parser.NewTypedComparisonExpr(
parser.In,
left.TypedLeft(),
<uple,
), nil
case parser.GT:
if i < len(ltuple) {
if ltuple[i].Compare(datum) == 0 {
ltuple = ltuple[i+1:]
} else {
ltuple = ltuple[i:]
}
if len(ltuple) > 0 {
return parser.NewTypedComparisonExpr(
parser.In,
left.TypedLeft(),
<uple,
), nil
}
}
return parser.MakeDBool(false), nil
case parser.GE:
if i < len(ltuple) {
ltuple = ltuple[i:]
if len(ltuple) > 0 {
return parser.NewTypedComparisonExpr(
parser.In,
left.TypedLeft(),
<uple,
), nil
}
}
return parser.MakeDBool(false), nil
case parser.LT:
if i < len(ltuple) {
if i == 0 {
return parser.MakeDBool(false), nil
}
ltuple = ltuple[:i]
return parser.NewTypedComparisonExpr(
parser.In,
left.TypedLeft(),
<uple,
), nil
}
return left, nil
case parser.LE:
if i < len(ltuple) {
if ltuple[i].Compare(datum) == 0 {
i++
}
if i == 0 {
return parser.MakeDBool(false), nil
}
ltuple = ltuple[:i]
return parser.NewTypedComparisonExpr(
parser.In,
left.TypedLeft(),
<uple,
), nil
}
return left, nil
}
case parser.In:
// Both of our tuples are sorted. Intersect the lists.
rtuple := *right.Right.(*parser.DTuple)
intersection := intersectSorted(ltuple, rtuple)
if len(*intersection) == 0 {
return parser.MakeDBool(false), nil
}
return parser.NewTypedComparisonExpr(
parser.In,
left.TypedLeft(),
intersection,
), nil
}
}
return origLeft, origRight
}
func simplifyOneAndExpr(left, right parser.TypedExpr) (parser.TypedExpr, parser.TypedExpr, bool) {
lcmp, ok := left.(*parser.ComparisonExpr)
if !ok {
return left, right, true
}
rcmp, ok := right.(*parser.ComparisonExpr)
if !ok {
return left, right, true
}
lcmpLeft, lcmpRight := lcmp.TypedLeft(), lcmp.TypedRight()
rcmpLeft, rcmpRight := rcmp.TypedLeft(), rcmp.TypedRight()
if !isDatum(lcmpRight) || !isDatum(rcmpRight) {
return parser.MakeDBool(true), nil, false
}
if !varEqual(lcmpLeft, rcmpLeft) {
return left, right, true
}
if lcmp.Operator == parser.IsNot || rcmp.Operator == parser.IsNot {
switch lcmp.Operator {
case parser.EQ, parser.GT, parser.GE, parser.LT, parser.LE, parser.In:
if rcmpRight == parser.DNull {
// a <cmp> x AND a IS NOT NULL
return left, nil, true
}
case parser.Is:
if lcmpRight == parser.DNull && rcmpRight == parser.DNull {
// a IS NULL AND a IS NOT NULL
return parser.MakeDBool(false), nil, true
}
case parser.IsNot:
if lcmpRight == parser.DNull {
switch rcmp.Operator {
case parser.EQ, parser.GT, parser.GE, parser.LT, parser.LE, parser.In:
// a IS NOT NULL AND a <cmp> x
return right, nil, true
case parser.Is:
if rcmpRight == parser.DNull {
// a IS NOT NULL AND a IS NULL
return parser.MakeDBool(false), nil, true
}
case parser.IsNot:
if rcmpRight == parser.DNull {
// a IS NOT NULL AND a IS NOT NULL
return left, nil, true
}
}
}
}
return left, right, true
}
if lcmp.Operator == parser.In || rcmp.Operator == parser.In {
left, right = simplifyOneAndInExpr(lcmp, rcmp)
return left, right, true
}
if reflect.TypeOf(lcmpRight) != reflect.TypeOf(rcmpRight) {
allowCmp := false
switch lcmp.Operator {
case parser.EQ, parser.NE, parser.GT, parser.GE, parser.LT, parser.LE:
switch rcmp.Operator {
case parser.EQ, parser.NE, parser.GT, parser.GE, parser.LT, parser.LE:
// Break, permitting heterogeneous comparison.
allowCmp = true
}
}
if !allowCmp {
if lcmp.Operator == parser.Is && lcmpRight == parser.DNull {
// a IS NULL AND a <cmp> x
return parser.MakeDBool(false), nil, true
}
if rcmp.Operator == parser.Is && rcmpRight == parser.DNull {
// a <cmp> x AND a IS NULL
return parser.MakeDBool(false), nil, true
}
// Note that "a IS NULL and a IS NULL" cannot happen here because
// "reflect.TypeOf(NULL) == reflect.TypeOf(NULL)".
return left, right, true
}
}
ldatum := lcmpRight.(parser.Datum)
rdatum := rcmpRight.(parser.Datum)
cmp := ldatum.Compare(rdatum)
// Determine which expression to use when either expression (left or right)
// is valid as a return value but their types are different. The reason
// to prefer a comparison between a column value and a datum of the same
// type is that it makes index constraint construction easier.
either := lcmp
if !ldatum.TypeEqual(rdatum) {
switch ta := lcmpLeft.(type) {
case *qvalue:
if ta.datum.TypeEqual(rdatum) {
either = rcmp
}
}
}
// TODO(pmattis): Figure out how to generate this logic.
switch lcmp.Operator {
case parser.EQ:
switch rcmp.Operator {
case parser.EQ:
// a = x AND a = y
if cmp == 0 {
// x = y
return either, nil, true
}
return parser.MakeDBool(false), nil, true
case parser.NE:
// a = x AND a != y
if cmp == 0 {
// x = y
return parser.MakeDBool(false), nil, true
}
return left, nil, true
case parser.GT, parser.GE:
// a = x AND (a > y OR a >= y)
if cmp == -1 || (cmp == 0 && rcmp.Operator == parser.GT) {
// x < y OR x = y
return parser.MakeDBool(false), nil, true
}
return left, nil, true
case parser.LT, parser.LE:
// a = x AND (a < y OR a <= y)
if cmp == 1 || (cmp == 0 && rcmp.Operator == parser.LT) {
// x > y OR x = y
return parser.MakeDBool(false), nil, true
}
return left, nil, true
}
case parser.NE:
switch rcmp.Operator {
case parser.EQ:
// a != x AND a = y
if cmp == 0 {
// x = y
return parser.MakeDBool(false), nil, true
}
return right, nil, true
case parser.NE:
// a != x AND a != y
if cmp == 0 {
// x = y
return either, nil, true
}
return left, right, true
case parser.GT:
// a != x AND a > y
return right, nil, cmp <= 0
case parser.LT:
// a != x AND a < y
return right, nil, cmp >= 0
case parser.GE:
// a != x AND a >= y
if cmp == 0 {
// x = y
return parser.NewTypedComparisonExpr(
parser.GT,
rcmpLeft,
either.TypedRight(),
), nil, true
}
// x != y
return right, nil, cmp == -1
case parser.LE:
// a != x AND a <= y
if cmp == 0 {
// x = y
return parser.NewTypedComparisonExpr(
parser.LT,
rcmpLeft,
either.TypedRight(),
), nil, true
}
// x != y
return right, nil, cmp == +1
}
case parser.GT:
switch rcmp.Operator {
case parser.EQ:
// a > x AND a = y
if cmp != -1 {
// x >= y
return parser.MakeDBool(false), nil, true
}
// x < y
return right, nil, true
case parser.NE:
// a > x AND a != y
return left, nil, cmp >= 0
case parser.GT, parser.GE:
// a > x AND (a > y OR a >= y)
if cmp != -1 {
// x >= y
return left, nil, true
}
// x < y
return right, nil, true
case parser.LT, parser.LE:
// a > x AND (a < y OR a <= y)
if cmp == -1 {
// x < y
return left, right, true
}
// x >= y
return parser.MakeDBool(false), nil, true
}
case parser.GE:
switch rcmp.Operator {
case parser.EQ:
// a >= x AND a = y
if cmp == 1 {
// x > y
return parser.MakeDBool(false), nil, true
}
// x <= y
return right, nil, true
case parser.NE:
// a >= x AND x != y
if cmp == 0 {
// x = y
return parser.NewTypedComparisonExpr(
parser.GT,
lcmpLeft,
either.TypedRight(),
), nil, true
}
// x != y
return left, nil, cmp == +1
case parser.GT, parser.GE:
// a >= x AND (a > y OR a >= y)
if cmp == -1 || (cmp == 0 && rcmp.Operator == parser.GT) {
// x < y
return right, nil, true
}
// x >= y
return left, nil, true
case parser.LT:
// a >= x AND a < y
if cmp == -1 {
// x < y
return left, right, true
}
// x >= y
return parser.MakeDBool(false), nil, true
case parser.LE:
// a >= x AND a <= y
if cmp == -1 {
// x < y
return left, right, true
} else if cmp == 0 {
// x = y
return parser.NewTypedComparisonExpr(
parser.EQ,
lcmpLeft,
either.TypedRight(),
), nil, true
}
// x > y
return parser.MakeDBool(false), nil, true
}
case parser.LT:
switch rcmp.Operator {
case parser.EQ:
// a < x AND a = y
if cmp != 1 {
// x <= y
return parser.MakeDBool(false), nil, true
}
// x > y
return right, nil, true
case parser.NE:
// a < x AND a != y
return left, nil, cmp <= 0
case parser.GT, parser.GE:
// a < x AND (a > y OR a >= y)
if cmp == 1 {
// x > y
return left, right, true
}
// x <= y
return parser.MakeDBool(false), nil, true
case parser.LT, parser.LE:
// a < x AND (a < y OR a <= y)
if cmp != 1 {
// x <= y
return left, nil, true
}
// x > y
return right, nil, true
}
case parser.LE:
switch rcmp.Operator {
case parser.EQ:
// a <= x AND a = y
if cmp == -1 {
// x < y
return parser.MakeDBool(false), nil, true
}
// x >= y
return right, nil, true
case parser.NE:
// a <= x AND a != y
if cmp == 0 {
// x = y
return parser.NewTypedComparisonExpr(
parser.LT,
lcmpLeft,
either.TypedRight(),
), nil, true
}
// x != y
return left, nil, cmp == -1
case parser.GT:
// a <= x AND a > y
if cmp == 1 {
// x > y
return left, right, true
}
return parser.MakeDBool(false), nil, true
case parser.GE:
// a <= x AND a >= y
if cmp == +1 {
// x > y
return left, right, true
} else if cmp == 0 {
// x = y
return parser.NewTypedComparisonExpr(
parser.EQ,
lcmpLeft,
either.TypedRight(),
), nil, true
}
// x < y
return parser.MakeDBool(false), nil, true
case parser.LT, parser.LE:
// a <= x AND (a > y OR a >= y)
if cmp == 1 || (cmp == 0 && rcmp.Operator == parser.LT) {
// x > y
return right, nil, true
}
// x <= y
return left, nil, true
}
case parser.Is:
switch rcmp.Operator {
case parser.Is:
if lcmpRight == parser.DNull && rcmpRight == parser.DNull {
// a IS NULL AND a IS NULL
return left, nil, true
}
}
}
return parser.MakeDBool(true), nil, false
}
func simplifyComparisonExpr(n *parser.ComparisonExpr) (parser.TypedExpr, bool) {
// NormalizeExpr will have left comparisons in the form "<var> <op>
// <datum>" unless they could not be simplified further in which case
// simplifyExpr cannot handle them. For example, "lower(a) = 'foo'"
left, right := n.TypedLeft(), n.TypedRight()
if isVar(left) && isDatum(right) {
if right == parser.DNull {
switch n.Operator {
case parser.IsNotDistinctFrom:
switch left.(type) {
case *qvalue, *parser.IndexedVar:
// Transform "a IS NOT DISTINCT FROM NULL" into "a IS NULL".
return parser.NewTypedComparisonExpr(
parser.Is,
left,
right,
), true
}
case parser.IsDistinctFrom:
switch left.(type) {
case *qvalue, *parser.IndexedVar:
// Transform "a IS DISTINCT FROM NULL" into "a IS NOT NULL".
return parser.NewTypedComparisonExpr(
parser.IsNot,
left,
right,
), true
}
case parser.Is, parser.IsNot:
switch left.(type) {
case *qvalue, *parser.IndexedVar:
// "a IS {,NOT} NULL" can be used during index selection to restrict
// the range of scanned keys.
return n, true
}
default:
// All of the remaining comparison operators have the property that when
// comparing to NULL they evaluate to NULL (see evalComparisonOp). NULL is
// not the same as false, but in the context of a WHERE clause, NULL is
// considered not-true which is the same as false.
return parser.MakeDBool(false), true
}
}
switch n.Operator {
case parser.EQ:
// Translate "(a, b) = (1, 2)" to "(a, b) IN ((1, 2))".
switch left.(type) {
case *parser.Tuple:
return parser.NewTypedComparisonExpr(
parser.In,
left,
&parser.DTuple{right.(parser.Datum)},
), true
}
return n, true
case parser.NE, parser.GE, parser.LE:
return n, true
case parser.GT:
// This simplification is necessary so that subsequent transformation of
// > constraint to >= can use Datum.Next without concern about whether a
// next value exists. Note that if the variable (n.Left) is NULL, this
// comparison would evaluate to NULL which is equivalent to false for a
// boolean expression.
if right.(parser.Datum).IsMax() {
return parser.MakeDBool(false), true
}
return n, true
case parser.LT:
// Note that if the variable is NULL, this would evaluate to NULL which
// would equivalent to false for a boolean expression.
if right.(parser.Datum).IsMin() {
return parser.MakeDBool(false), true
}
return n, true
case parser.In, parser.NotIn:
tuple := *right.(*parser.DTuple)
if len(tuple) == 0 {
return parser.MakeDBool(false), true
}
return n, true
case parser.Like:
// a LIKE 'foo%' -> a >= "foo" AND a < "fop"
if d, ok := right.(*parser.DString); ok {
if i := strings.IndexAny(string(*d), "_%"); i >= 0 {
return makePrefixRange((*d)[:i], left, false), false
}
return makePrefixRange(*d, left, true), false
}
// TODO(pmattis): Support parser.DBytes?
case parser.SimilarTo:
// a SIMILAR TO "foo.*" -> a >= "foo" AND a < "fop"
if d, ok := right.(*parser.DString); ok {
pattern := parser.SimilarEscape(string(*d))
if re, err := regexp.Compile(pattern); err == nil {
prefix, complete := re.LiteralPrefix()
return makePrefixRange(parser.DString(prefix), left, complete), false
}
}
// TODO(pmattis): Support parser.DBytes?
}
}
return parser.MakeDBool(true), false
}
func simplifyOneOrInExpr(left, right *parser.ComparisonExpr) (parser.TypedExpr, parser.TypedExpr) {
if left.Operator != parser.In && right.Operator != parser.In {
panic(fmt.Sprintf("IN expression required: %s vs %s", left, right))
}
origLeft, origRight := left, right
switch left.Operator {
case parser.EQ, parser.NE, parser.GT, parser.GE, parser.LT, parser.LE:
switch right.Operator {
case parser.In:
left, right = right, left
}
fallthrough
case parser.In:
tuple := *left.Right.(*parser.DTuple)
switch right.Operator {
case parser.EQ:
datum := right.Right.(parser.Datum)
// We keep the tuples for an IN expression in sorted order. So now we just
// merge the two sorted lists.
return parser.NewTypedComparisonExpr(
parser.In,
left.TypedLeft(),
mergeSorted(tuple, parser.DTuple{datum}),
), nil
case parser.NE, parser.GT, parser.GE, parser.LT, parser.LE:
datum := right.Right.(parser.Datum)
i := sort.Search(len(tuple), func(i int) bool {
return tuple[i].(parser.Datum).Compare(datum) >= 0
})
switch right.Operator {
case parser.NE:
if i < len(tuple) && tuple[i].Compare(datum) == 0 {
return makeIsNotNull(right.TypedLeft()), nil
}
return right, nil
case parser.GT:
if i == 0 {
// datum >= tuple[0]
if tuple[i].Compare(datum) == 0 {
// datum = tuple[0]
return parser.NewTypedComparisonExpr(
parser.GE,
left.TypedLeft(),
datum,
), nil
}
return right, nil
}
case parser.GE:
if i == 0 {
// datum >= tuple[0]
return right, nil
}
case parser.LT:
if i == len(tuple) {
// datum > tuple[len(tuple)-1]
return right, nil
} else if i == len(tuple)-1 {
// datum >= tuple[len(tuple)-1]
if tuple[i].Compare(datum) == 0 {
// datum == tuple[len(tuple)-1]
return parser.NewTypedComparisonExpr(
parser.LE,
left.TypedLeft(),
datum,
), nil
}
}
case parser.LE:
if i == len(tuple) ||
(i == len(tuple)-1 && tuple[i].Compare(datum) == 0) {
// datum >= tuple[len(tuple)-1]
return right, nil
}
}
case parser.In:
// We keep the tuples for an IN expression in sorted order. So now we
// just merge the two sorted lists.
return parser.NewTypedComparisonExpr(
parser.In,
left.TypedLeft(),
mergeSorted(tuple, *right.Right.(*parser.DTuple)),
), nil
}
}
return origLeft, origRight
}
// makeIndexConstraints generates constraints for a set of conjunctions (AND
// expressions). These expressions can be the entire filter, or they can be one
// of multiple top-level disjunctions (ORs).
//
// The constraints consist of start and end expressions for a prefix of the
// columns that make up the index. For example, consider the expression
// "a >= 1 AND b >= 2":
//
// {a: {start: >= 1}, b: {start: >= 2}}
//
// This method generates one indexConstraint for a prefix of the columns in
// the index (except for tuple constraints which can account for more than
// one column). A prefix of the generated constraints has a .start, and
// similarly a prefix of the contraints has a .end (in other words,
// once a constraint doesn't have a .start, no further constraints will
// have one). This is because they wouldn't be useful when generating spans.
//
// makeIndexConstraints takes into account the direction of the columns in the
// index. For ascending cols, start constraints look for comparison expressions
// with the operators >, >=, = or IN and end constraints look for comparison
// expressions with the operators <, <=, = or IN. Vice versa for descending
// cols.
//
// Whenever possible, < and > are converted to <= and >=, respectively.
// This is because we can use inclusive constraints better than exclusive ones;
// with inclusive constraints we can continue to accumulate constraints for
// next columns. Not so with exclusive ones: Consider "a < 1 AND b < 2".
// "a < 1" will be encoded as an exclusive span end; if we were to append
// anything about "b" to it, that would be incorrect.
// Note that it's not always possible to transform ">" to ">=", because some
// types do not support the Next() operation. Similarly, it is not always possible
// to transform "<" to "<=", because some types do not support the Prev() operation.
// So, the resulting constraints might contain ">" or "<" (depending on encoding
// direction), in which case that will be the last constraint with `.end` filled.
//
// TODO(pmattis): It would be more obvious to perform this transform in
// simplifyComparisonExpr, but doing so there eliminates some of the other
// simplifications. For example, "a < 1 OR a > 1" currently simplifies to "a !=
// 1", but if we performed this transform in simpilfyComparisonExpr it would
// simplify to "a < 1 OR a >= 2" which is also the same as "a != 1", but not so
// obvious based on comparisons of the constants.
func (v *indexInfo) makeIndexConstraints(andExprs parser.TypedExprs) (indexConstraints, error) {
var constraints indexConstraints
trueStartDone := false
trueEndDone := false
for i := 0; i < len(v.index.ColumnIDs); i++ {
colID := v.index.ColumnIDs[i]
var colDir encoding.Direction
var err error
if colDir, err = v.index.ColumnDirections[i].ToEncodingDirection(); err != nil {
return nil, err
}
var constraint indexConstraint
// We're going to fill in that start and end of the constraint
// by indirection, which keeps in mind the direction of the
// column's encoding in the index.
// This allows us to produce direction-aware constraints, but
// still have the code below be intuitive (e.g. treat ">" always as
// a start constraint).
startExpr := &constraint.start
endExpr := &constraint.end
startDone := &trueStartDone
endDone := &trueEndDone
if colDir == encoding.Descending {
// For descending index cols, c.start is an end constraint
// and c.end is a start constraint.
startExpr = &constraint.end
endExpr = &constraint.start
startDone = &trueEndDone
endDone = &trueStartDone
}
exprLoop:
for _, e := range andExprs {
if c, ok := e.(*parser.ComparisonExpr); ok {
var tupleMap []int
if ok, colIdx := getQValColIdx(c.Left); ok && v.desc.Columns[colIdx].ID != colID {
// This expression refers to a column other than the one we're
// looking for.
continue
}
if _, ok := c.Right.(parser.Datum); !ok {
continue
}
if t, ok := c.Left.(*parser.Tuple); ok {
// If we have a tuple comparison we need to rearrange the comparison
// so that the order of the columns in the tuple matches the order in
// the index. For example, for an index on (a, b), the tuple
// comparison "(b, a) = (1, 2)" would be rewritten as "(a, b) = (2,
// 1)". Note that we don't actually need to rewrite the comparison,
// but simply provide a mapping from the order in the tuple to the
// order in the index.
for _, colID := range v.index.ColumnIDs[i:] {
idx := -1
for i, val := range t.Exprs {
ok, colIdx := getQValColIdx(val)
if ok && v.desc.Columns[colIdx].ID == colID {
idx = i
break
}
}
if idx == -1 {
break
}
tupleMap = append(tupleMap, idx)
}
if len(tupleMap) == 0 {
// This tuple does not contain the column we're looking for.
continue
}
// Skip all the next columns covered by this tuple.
i += (len(tupleMap) - 1)
if c.Operator != parser.In {
// Make sure all columns specified in the tuple are in the index.
// TODO(mjibson): support prefixes: (a,b,c) > (1,2,3) -> (a,b) >= (1,2)
if len(t.Exprs) > len(tupleMap) {
continue
}
// Since tuples comparison is lexicographic, we only support it if the tuple
// is in the same order as the index.
for i, v := range tupleMap {
if i != v {
continue exprLoop
}
}
// Due to the implementation of the encoding functions, it is currently
// difficult to support indexes of varying directions with tuples. For now,
// restrict them to a single direction. See #6346.
dir := v.index.ColumnDirections[i]
for _, ti := range tupleMap {
if dir != v.index.ColumnDirections[ti] {
continue exprLoop
}
}
}
constraint.tupleMap = tupleMap
}
preStart := *startExpr
preEnd := *endExpr
switch c.Operator {
case parser.EQ:
// An equality constraint will overwrite any other type
// of constraint.
if !*startDone {
*startExpr = c
}
if !*endDone {
*endExpr = c
}
case parser.NE:
// We rewrite "a != x" to "a IS NOT NULL", since this is all that
// makeSpans() cares about.
// We don't simplify "a != x" to "a IS NOT NULL" in
// simplifyExpr because doing so affects other simplifications.
if *startDone || *startExpr != nil {
continue
}
*startExpr = parser.NewTypedComparisonExpr(
parser.IsNot,
c.TypedLeft(),
parser.DNull,
)
case parser.In:
// Only allow the IN constraint if the previous constraints are all
// EQ. This is necessary to prevent overlapping spans from being
// generated. Consider the constraints [a >= 1, a <= 2, b IN (1,
// 2)]. This would turn into the spans /1/1-/3/2 and /1/2-/3/3.
ok := true
for _, c := range constraints {
ok = ok && (c.start == c.end) && (c.start.Operator == parser.EQ)
}
if !ok {
continue
}
if !*startDone && (*startExpr == nil || (*startExpr).Operator != parser.EQ) {
*startExpr = c
}
if !*endDone && (*endExpr == nil || (*endExpr).Operator != parser.EQ) {
*endExpr = c
}
case parser.GE:
if !*startDone && *startExpr == nil {
*startExpr = c
}
case parser.GT:
// Transform ">" into ">=".
if *startDone || (*startExpr != nil) {
continue
}
if c.Right.(parser.Datum).IsMax() {
*startExpr = parser.NewTypedComparisonExpr(
parser.EQ,
c.TypedLeft(),
c.TypedRight(),
)
} else if c.Right.(parser.Datum).HasNext() {
*startExpr = parser.NewTypedComparisonExpr(
parser.GE,
c.TypedLeft(),
c.Right.(parser.Datum).Next(),
)
} else {
*startExpr = c
}
case parser.LT:
if *endDone || (*endExpr != nil) {
continue
}
// Transform "<" into "<=".
if c.Right.(parser.Datum).IsMin() {
*endExpr = parser.NewTypedComparisonExpr(
parser.EQ,
c.TypedLeft(),
c.TypedRight(),
)
} else if c.Right.(parser.Datum).HasPrev() {
*endExpr = parser.NewTypedComparisonExpr(
parser.LE,
c.TypedLeft(),
c.Right.(parser.Datum).Prev(),
)
} else {
*endExpr = c
}
case parser.LE:
if !*endDone && *endExpr == nil {
*endExpr = c
}
case parser.Is:
if c.Right == parser.DNull && !*endDone {
*endExpr = c
}
case parser.IsNot:
if c.Right == parser.DNull && !*startDone && (*startExpr == nil) {
*startExpr = c
}
}
// If a new constraint includes a mixed-type comparison expression,
// we can not include it in the index constraints because the index
// encoding would be incorrect. See #4313.
if preStart != *startExpr {
if isMixedTypeComparison(*startExpr) {
*startExpr = nil
}
}
if preEnd != *endExpr {
if isMixedTypeComparison(*endExpr) {
*endExpr = nil
}
}
}
}
if *endExpr != nil && (*endExpr).Operator == parser.LT {
*endDone = true
}
if !*startDone && *startExpr == nil {
// Add an IS NOT NULL constraint if there's an end constraint.
if (*endExpr != nil) &&
!((*endExpr).Operator == parser.Is && (*endExpr).Right == parser.DNull) {
*startExpr = parser.NewTypedComparisonExpr(
parser.IsNot,
(*endExpr).TypedLeft(),
parser.DNull,
)
}
}
if (*startExpr == nil) ||
(((*startExpr).Operator == parser.IsNot) && ((*startExpr).Right == parser.DNull)) {
// There's no point in allowing future start constraints after an IS NOT NULL
// one; since NOT NULL is not actually a value present in an index,
// values encoded after an NOT NULL don't matter.
*startDone = true
}
if constraint.start != nil || constraint.end != nil {
constraints = append(constraints, constraint)
}
if *endExpr == nil {
*endDone = true
}
if *startDone && *endDone {
// The rest of the expressions don't matter; when we construct index spans
// based on these constraints we won't be able to accumulate more in either
// the start key prefix nor the end key prefix.
break
}
}
return constraints, nil
}
