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Fix complex predicates being pulled into `ON` conditions for `LEFT JOIN` statements. (#11317)
* Fix complex predicates being pulled into `ON` conditions for `LEFT JOIN` statements. Also convert `LEFT JOIN` statements with complex predicates into `INNER JOIN` when possible. Signed-off-by: Arthur Schreiber <arthurschreiber@github.com> * Allow outer join simplification for `IS NOT NULL` expressions. Signed-off-by: Arthur Schreiber <arthurschreiber@github.com> Signed-off-by: Arthur Schreiber <arthurschreiber@github.com>
This commit is contained in:
Arthur Schreiber
GitHub
Родитель
bf6aa7c197
Коммит
8af0a03838
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@ -46,22 +46,10 @@ func (j *Join) PushPredicate(expr sqlparser.Expr, semTable *semantics.SemTable)
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}
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j.LHS = lhs
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return j, nil
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case deps.IsSolvedBy(j.RHS.TableID()):
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// we are looking for predicates like `tbl.col = <>` or `<> = tbl.col`,
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// where tbl is on the rhs of the left outer join
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if cmp, isCmp := expr.(*sqlparser.ComparisonExpr); isCmp && cmp.Operator != sqlparser.NullSafeEqualOp &&
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(sqlparser.IsColName(cmp.Left) && semTable.RecursiveDeps(cmp.Left).IsSolvedBy(j.RHS.TableID()) ||
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sqlparser.IsColName(cmp.Right) && semTable.RecursiveDeps(cmp.Right).IsSolvedBy(j.RHS.TableID())) {
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// When the predicate we are pushing is using information from an outer table, we can
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// check whether the predicate is "null-intolerant" or not. Null-intolerant in this context means that
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// the predicate will not return true if the table columns are null.
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// Since an outer join is an inner join with the addition of all the rows from the left-hand side that
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// matched no rows on the right-hand, if we are later going to remove all the rows where the right-hand
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// side did not match, we might as well turn the join into an inner join.
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// This is based on the paper "Canonical Abstraction for Outerjoin Optimization" by J Rao et al
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j.LeftJoin = false
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}
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case deps.IsSolvedBy(j.RHS.TableID()):
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j.tryConvertToInnerJoin(expr, semTable)
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if !j.LeftJoin {
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rhs, err := j.RHS.PushPredicate(expr, semTable)
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if err != nil {
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@ -70,19 +58,68 @@ func (j *Join) PushPredicate(expr sqlparser.Expr, semTable *semantics.SemTable)
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j.RHS = rhs
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return j, err
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}
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op := &Filter{
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Source: j,
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Predicates: []sqlparser.Expr{expr},
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}
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return op, nil
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case deps.IsSolvedBy(j.LHS.TableID().Merge(j.RHS.TableID())):
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j.Predicate = sqlparser.AndExpressions(j.Predicate, expr)
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return j, nil
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j.tryConvertToInnerJoin(expr, semTable)
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if !j.LeftJoin {
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j.Predicate = sqlparser.AndExpressions(j.Predicate, expr)
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return j, nil
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}
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op := &Filter{
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Source: j,
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Predicates: []sqlparser.Expr{expr},
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}
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return op, nil
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}
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return nil, vterrors.Errorf(vtrpcpb.Code_INTERNAL, "Cannot push predicate: %s", sqlparser.String(expr))
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}
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// When a predicate uses information from an outer table, we can convert from an outer join to an inner join
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// if the predicate is "null-intolerant".
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//
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// Null-intolerant in this context means that the predicate will not be true if the table columns are null.
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//
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// Since an outer join is an inner join with the addition of all the rows from the left-hand side that
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// matched no rows on the right-hand, if we are later going to remove all the rows where the right-hand
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// side did not match, we might as well turn the join into an inner join.
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//
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// This is based on the paper "Canonical Abstraction for Outerjoin Optimization" by J Rao et al
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func (j *Join) tryConvertToInnerJoin(expr sqlparser.Expr, semTable *semantics.SemTable) {
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if !j.LeftJoin {
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return
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}
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switch expr := expr.(type) {
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case *sqlparser.ComparisonExpr:
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if expr.Operator == sqlparser.NullSafeEqualOp {
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return
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}
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if sqlparser.IsColName(expr.Left) && semTable.RecursiveDeps(expr.Left).IsSolvedBy(j.RHS.TableID()) ||
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sqlparser.IsColName(expr.Right) && semTable.RecursiveDeps(expr.Right).IsSolvedBy(j.RHS.TableID()) {
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j.LeftJoin = false
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}
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case *sqlparser.IsExpr:
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if expr.Right != sqlparser.IsNotNullOp {
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return
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}
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if sqlparser.IsColName(expr.Left) && semTable.RecursiveDeps(expr.Left).IsSolvedBy(j.RHS.TableID()) {
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j.LeftJoin = false
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}
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}
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}
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// TableID implements the Operator interface
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func (j *Join) TableID() semantics.TableSet {
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return j.RHS.TableID().Merge(j.LHS.TableID())
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@ -5965,6 +5965,114 @@ Gen4 plan same as above
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}
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Gen4 plan same as above
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# For left joins, where conditions using both sides of the join are not pulled into the join conditions
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"SELECT music.id FROM music LEFT OUTER JOIN user ON music.user_id = user.id WHERE (user.name = 'Trent Reznor' OR music.genre = 'pop') AND music.user_id = 5"
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{
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"QueryType": "SELECT",
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"Original": "SELECT music.id FROM music LEFT OUTER JOIN user ON music.user_id = user.id WHERE (user.name = 'Trent Reznor' OR music.genre = 'pop') AND music.user_id = 5",
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"Instructions": {
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"OperatorType": "Route",
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"Variant": "EqualUnique",
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"Keyspace": {
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"Name": "user",
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"Sharded": true
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},
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"FieldQuery": "select music.id from music left join `user` on music.user_id = `user`.id where 1 != 1",
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"Query": "select music.id from music left join `user` on music.user_id = `user`.id where music.user_id = 5 and (`user`.`name` = 'Trent Reznor' or music.genre = 'pop')",
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"Table": "`user`, music",
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"Values": [
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"INT64(5)"
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],
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"Vindex": "user_index"
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},
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"TablesUsed": [
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"user.music",
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"user.user"
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]
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}
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Gen4 plan same as above
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# For left joins, where conditions using both sides of the join are not pulled into the join conditions (swapped order)
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"SELECT music.id FROM music LEFT OUTER JOIN user ON music.user_id = user.id WHERE music.user_id = 5 AND (user.name = 'Trent Reznor' OR music.genre = 'pop')"
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{
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"QueryType": "SELECT",
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"Original": "SELECT music.id FROM music LEFT OUTER JOIN user ON music.user_id = user.id WHERE music.user_id = 5 AND (user.name = 'Trent Reznor' OR music.genre = 'pop')",
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"Instructions": {
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"OperatorType": "Route",
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"Variant": "EqualUnique",
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"Keyspace": {
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"Name": "user",
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"Sharded": true
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},
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"FieldQuery": "select music.id from music left join `user` on music.user_id = `user`.id where 1 != 1",
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"Query": "select music.id from music left join `user` on music.user_id = `user`.id where music.user_id = 5 and (`user`.`name` = 'Trent Reznor' or music.genre = 'pop')",
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"Table": "`user`, music",
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"Values": [
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"INT64(5)"
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],
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"Vindex": "user_index"
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},
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"TablesUsed": [
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"user.music",
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"user.user"
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]
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}
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Gen4 plan same as above
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# For left joins, null intolerant where conditions using both sides of the join are transformed to inner joins
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"SELECT music.id FROM music LEFT OUTER JOIN user ON music.user_id = user.id WHERE music.user_id = 5 AND music.componist = user.name"
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{
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"QueryType": "SELECT",
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"Original": "SELECT music.id FROM music LEFT OUTER JOIN user ON music.user_id = user.id WHERE music.user_id = 5 AND music.componist = user.name",
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"Instructions": {
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"OperatorType": "Route",
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"Variant": "EqualUnique",
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"Keyspace": {
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"Name": "user",
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"Sharded": true
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},
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"FieldQuery": "select music.id from music, `user` where 1 != 1",
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"Query": "select music.id from music, `user` where music.user_id = 5 and music.user_id = `user`.id and music.componist = `user`.`name`",
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"Table": "`user`, music",
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"Values": [
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"INT64(5)"
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],
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"Vindex": "user_index"
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},
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"TablesUsed": [
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"user.music",
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"user.user"
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]
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}
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Gen4 plan same as above
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# For left joins, null intolerant where conditions using `IS NOT NULL` allow outer join simplification
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"SELECT music.id FROM music LEFT OUTER JOIN user ON user.id = music.user_id WHERE music.user_id = 5 AND user.id IS NOT NULL"
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{
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"QueryType": "SELECT",
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"Original": "SELECT music.id FROM music LEFT OUTER JOIN user ON user.id = music.user_id WHERE music.user_id = 5 AND user.id IS NOT NULL",
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"Instructions": {
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"OperatorType": "Route",
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"Variant": "EqualUnique",
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"Keyspace": {
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"Name": "user",
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"Sharded": true
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},
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"FieldQuery": "select music.id from music, `user` where 1 != 1",
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"Query": "select music.id from music, `user` where music.user_id = 5 and `user`.id is not null and `user`.id = music.user_id",
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"Table": "`user`, music",
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"Values": [
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"INT64(5)"
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],
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"Vindex": "user_index"
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},
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"TablesUsed": [
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"user.music",
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"user.user"
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]
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}
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Gen4 plan same as above
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# optimize ORs to IN route op codes #1
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"select col from user where id = 1 or id = 2"
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{
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