forked from cockroachdb/cockroach
-
Notifications
You must be signed in to change notification settings - Fork 0
/
data_source.go
901 lines (815 loc) · 28.4 KB
/
data_source.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
// Copyright 2016 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
package sql
import (
"bytes"
"fmt"
"github.com/pkg/errors"
"golang.org/x/net/context"
"github.com/cockroachdb/cockroach/pkg/security"
"github.com/cockroachdb/cockroach/pkg/sql/parser"
"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgerror"
"github.com/cockroachdb/cockroach/pkg/sql/privilege"
"github.com/cockroachdb/cockroach/pkg/sql/sqlbase"
)
// To understand dataSourceInfo below it is crucial to understand the
// meaning of a "data source" and its relationship to names/IndexedVars.
//
// A data source is an object that can deliver rows of column data,
// where each row is implemented in CockroachDB as an array of values.
// The defining property of a data source is that the columns in its
// result row arrays are always 0-indexed.
//
// From the language perspective, data sources are defined indirectly by:
// - the FROM clause in a SELECT statement;
// - JOIN clauses within the FROM clause;
// - the clause that follows INSERT INTO colName(Cols...);
// - the clause that follows UPSERT ....;
// - the invisible data source defined by the original table row during
// UPSERT, if it exists.
//
// Most expressions (parser.Expr trees) in CockroachDB refer to a
// single data source. A notable exception is UPSERT, where expressions
// can refer to two sources: one for the values being inserted, one for
// the original row data in the table for the conflicting (already
// existing) rows.
//
// Meanwhile, IndexedVars in CockroachDB provide the interface between
// symbolic names in expressions (e.g. "f.x", called VarNames,
// or names) and data sources. During evaluation, an IndexedVar must
// resolve to a column value. For a given name there are thus two
// subsequent questions that must be answered:
//
// - which data source is the name referring to? (when there is more than 1 source)
// - which 0-indexed column in that data source is the name referring to?
//
// The IndexedVar must distinguish data sources because the same column index
// may refer to different columns in different data sources. For
// example in an UPSERT statement the IndexedVar for "excluded.x" could refer
// to column 0 in the (already existing) table row, whereas "src.x" could
// refer to column 0 in the valueNode that provides values to insert.
//
// Within this context, the infrastructure for data sources and IndexedVars
// is implemented as follows:
//
// - dataSourceInfo provides column metadata for exactly one data source;
// - multiSourceInfo is an array of one or more dataSourceInfo
// - the index in IndexedVars points to one of the columns in the
// logical concatenation of all items in the multiSourceInfo;
// - IndexedVarResolver (select_name_resolution.go) is tasked with
// linking back IndexedVars with their data source and column index.
//
// This being said, there is a misunderstanding one should be careful
// to avoid: *there is no direct relationship between data sources and
// table names* in SQL. In other words:
//
// - the same table name can be present in two or more data sources; for example
// with:
// INSERT INTO excluded VALUES (42) ON CONFLICT (x) DO UPDATE ...
// the name "excluded" can refer either to the data source for VALUES(42)
// or the implicit data source corresponding to the rows in the original table
// that conflict with the new values.
//
// When this happens, a name of the form "excluded.x" must be
// resolved by considering all the data sources; if there is more
// than one data source providing the table name "excluded" (as in
// this case), the query is rejected with an ambiguity error.
//
// - a single data source may provide values for multiple table names; for
// example with:
// SELECT * FROM (f CROSS JOIN g) WHERE f.x = g.x
// there is a single data source corresponding to the results of the
// CROSS JOIN, providing a single 0-indexed array of values on each
// result row.
//
// (multiple table names for a single data source happen in JOINed sources
// and JOINed sources only. Note that a FROM clause with a comma-separated
// list of sources is a CROSS JOIN in disguise.)
//
// When this happens, names of the form "f.x" in either WHERE,
// SELECT renders, or other expressions which can refer to the data
// source do not refer to the "internal" data sources of the JOIN;
// they always refer to the final result rows of the JOIN source as
// a whole.
//
// This implies that a single dataSourceInfo that provides metadata
// for a complex JOIN clause must "know" which table name is
// associated with each column in its result set.
//
type dataSourceInfo struct {
// sourceColumns match the plan.Columns() 1-to-1. However the column
// names might be different if the statement renames them using AS.
sourceColumns sqlbase.ResultColumns
// sourceAliases indicates to which table alias column ranges
// belong.
// These often correspond to the original table names for each
// column but might be different if the statement renames
// them using AS.
sourceAliases sourceAliases
}
// planDataSource contains the data source information for data
// produced by a planNode.
type planDataSource struct {
// info which describe the columns.
info *dataSourceInfo
// plan which can be used to retrieve the data.
plan planNode
}
// columnRange identifies a non-empty set of columns in a
// selection. This is used by dataSourceInfo.sourceAliases to map
// table names to column ranges.
type columnRange []int
// sourceAlias associates a table name (alias) to a set of columns in the result
// row of a data source.
type sourceAlias struct {
name parser.TableName
columnRange columnRange
}
func (src *dataSourceInfo) String() string {
var buf bytes.Buffer
for i := range src.sourceColumns {
if i > 0 {
buf.WriteByte('\t')
}
fmt.Fprintf(&buf, "%d", i)
}
buf.WriteString("\toutput column positions\n")
for i, c := range src.sourceColumns {
if i > 0 {
buf.WriteByte('\t')
}
if c.Hidden {
buf.WriteByte('*')
}
buf.WriteString(c.Name)
}
buf.WriteString("\toutput column names\n")
for _, a := range src.sourceAliases {
for i := range src.sourceColumns {
if i > 0 {
buf.WriteByte('\t')
}
for _, j := range a.columnRange {
if i == j {
buf.WriteString("x")
break
}
}
}
if a.name == anonymousTable {
buf.WriteString("\t<anonymous table>")
} else {
fmt.Fprintf(&buf, "\t'%s'", a.name.String())
}
fmt.Fprintf(&buf, " - %q\n", a.columnRange)
}
return buf.String()
}
type sourceAliases []sourceAlias
// srcIdx looks up a source by qualified name and returns the index of the
// source (and whether we found one).
func (s sourceAliases) srcIdx(name parser.TableName) (srcIdx int, found bool) {
for i := range s {
if s[i].name.DatabaseName == name.DatabaseName && s[i].name.TableName == name.TableName {
return i, true
}
}
return -1, false
}
// columnRange looks up a source by name and returns the column range (and
// whether we found the name).
func (s sourceAliases) columnRange(name parser.TableName) (colRange columnRange, found bool) {
idx, ok := s.srcIdx(name)
if !ok {
return nil, false
}
return s[idx].columnRange, true
}
// anonymousTable is the empty table name, used when a data source
// has no own name, e.g. VALUES, subqueries or the empty source.
var anonymousTable = parser.TableName{}
// fillColumnRange creates a single range that refers to all the
// columns between firstIdx and lastIdx, inclusive.
func fillColumnRange(firstIdx, lastIdx int) columnRange {
res := make(columnRange, lastIdx-firstIdx+1)
for i := range res {
res[i] = i + firstIdx
}
return res
}
// newSourceInfoForSingleTable creates a simple dataSourceInfo
// which maps the same tableAlias to all columns.
func newSourceInfoForSingleTable(
tn parser.TableName, columns sqlbase.ResultColumns,
) *dataSourceInfo {
return &dataSourceInfo{
sourceColumns: columns,
sourceAliases: sourceAliases{{name: tn, columnRange: fillColumnRange(0, len(columns)-1)}},
}
}
// getSources combines zero or more FROM sources into cross-joins.
func (p *planner) getSources(
ctx context.Context, sources []parser.TableExpr, scanVisibility scanVisibility,
) (planDataSource, error) {
switch len(sources) {
case 0:
plan := &unaryNode{}
return planDataSource{
info: newSourceInfoForSingleTable(anonymousTable, planColumns(plan)),
plan: plan,
}, nil
case 1:
return p.getDataSource(ctx, sources[0], nil, scanVisibility)
default:
left, err := p.getDataSource(ctx, sources[0], nil, scanVisibility)
if err != nil {
return planDataSource{}, err
}
right, err := p.getSources(ctx, sources[1:], scanVisibility)
if err != nil {
return planDataSource{}, err
}
return p.makeJoin(ctx, "CROSS JOIN", left, right, nil)
}
}
// getVirtualDataSource attempts to find a virtual table with the
// given name.
func (p *planner) getVirtualDataSource(
ctx context.Context, tn *parser.TableName,
) (planDataSource, bool, error) {
virtual, err := p.session.virtualSchemas.getVirtualTableEntry(tn)
if err != nil {
return planDataSource{}, false, err
}
if virtual.desc != nil {
columns, constructor := virtual.getPlanInfo(ctx)
// The virtual table constructor takes the target database
// as "prefix" argument. This is either the prefix in the
// virtual table name given in the SQL query explicitly,
// or, if no prefix is given,
// the current database if one is set,
// or the empty prefix if the user is root (to show everything),
// or "system" otherwise (to only show virt tables to non-root users).
//
// It is particularly important to not use the empty prefix for
// non-root users, because client libraries that mistakenly do not
// set a current database tend to be badly, badly behaved if they
// see tables from multiple databases (as in, "drop tables from
// the wrong db" mis-behaved). Lack of data in the vtable in the
// case where there is no current database is thus safer.
//
// Meanwhile the root user probably would be inconvenienced by
// this.
prefix := string(tn.PrefixName)
if !tn.PrefixOriginallySpecified {
prefix = p.session.Database
if prefix == "" && p.session.User != security.RootUser {
prefix = sqlbase.SystemDB.Name
}
}
// Define the name of the source visible in EXPLAIN(NOEXPAND).
sourceName := parser.TableName{
PrefixName: parser.Name(prefix),
TableName: parser.Name(virtual.desc.Name),
DatabaseName: tn.DatabaseName,
}
// The resulting node.
return planDataSource{
info: newSourceInfoForSingleTable(sourceName, columns),
plan: &delayedNode{
name: sourceName.String(),
columns: columns,
constructor: func(ctx context.Context, p *planner) (planNode, error) {
return constructor(ctx, p, prefix)
},
},
}, true, nil
}
return planDataSource{}, false, nil
}
// getDataSource builds a planDataSource from a single data source clause
// (TableExpr) in a SelectClause.
func (p *planner) getDataSource(
ctx context.Context,
src parser.TableExpr,
hints *parser.IndexHints,
scanVisibility scanVisibility,
) (planDataSource, error) {
switch t := src.(type) {
case *parser.NormalizableTableName:
// Usual case: a table.
tn, err := p.QualifyWithDatabase(ctx, t)
if err != nil {
return planDataSource{}, err
}
// Is this perhaps a name for a virtual table?
ds, foundVirtual, err := p.getVirtualDataSource(ctx, tn)
if err != nil {
return planDataSource{}, err
}
if foundVirtual {
return ds, nil
}
return p.getTableScanOrViewPlan(ctx, tn, hints, scanVisibility)
case *parser.FuncExpr:
return p.getGeneratorPlan(ctx, t)
case *parser.Subquery:
return p.getSubqueryPlan(ctx, anonymousTable, t.Select, nil)
case *parser.JoinTableExpr:
// Joins: two sources.
left, err := p.getDataSource(ctx, t.Left, nil, scanVisibility)
if err != nil {
return left, err
}
right, err := p.getDataSource(ctx, t.Right, nil, scanVisibility)
if err != nil {
return right, err
}
return p.makeJoin(ctx, t.Join, left, right, t.Cond)
case *parser.StatementSource:
plan, err := p.newPlan(ctx, t.Statement, nil)
if err != nil {
return planDataSource{}, err
}
return planDataSource{
info: newSourceInfoForSingleTable(anonymousTable, planColumns(plan)),
plan: plan,
}, nil
case *parser.ParenTableExpr:
return p.getDataSource(ctx, t.Expr, hints, scanVisibility)
case *parser.TableRef:
return p.getTableScanByRef(ctx, t, hints, scanVisibility)
case *parser.AliasedTableExpr:
// Alias clause: source AS alias(cols...)
if t.Hints != nil {
hints = t.Hints
}
src, err := p.getDataSource(ctx, t.Expr, hints, scanVisibility)
if err != nil {
return src, err
}
if t.Ordinality {
// The WITH ORDINALITY clause numbers the rows coming out of the
// data source. See the comments next to the definition of
// `ordinalityNode` in particular how this restricts
// optimizations.
src = p.wrapOrdinality(src)
}
return renameSource(src, t.As, false)
default:
return planDataSource{}, errors.Errorf("unsupported FROM type %T", src)
}
}
func (p *planner) QualifyWithDatabase(
ctx context.Context, t *parser.NormalizableTableName,
) (*parser.TableName, error) {
tn, err := t.Normalize()
if err != nil {
return nil, err
}
if tn.DatabaseName == "" {
if err := p.searchAndQualifyDatabase(ctx, tn); err != nil {
return nil, err
}
}
return tn, nil
}
func (p *planner) getTableDescByID(
ctx context.Context, tableID sqlbase.ID,
) (*sqlbase.TableDescriptor, error) {
descFunc := p.session.tables.getTableVersionByID
if p.avoidCachedDescriptors {
descFunc = sqlbase.GetTableDescFromID
}
return descFunc(ctx, p.txn, tableID)
}
func (p *planner) getTableScanByRef(
ctx context.Context,
tref *parser.TableRef,
hints *parser.IndexHints,
scanVisibility scanVisibility,
) (planDataSource, error) {
desc, err := p.getTableDescByID(ctx, sqlbase.ID(tref.TableID))
if err != nil {
return planDataSource{}, errors.Errorf("%s: %v", parser.ErrString(tref), err)
}
tn := parser.TableName{
TableName: parser.Name(desc.Name),
// Ideally, we'd like to populate DatabaseName here, however that
// would require a reverse-lookup from DB ID to database name, and
// we do not provide an API to do this without a KV lookup. The
// cost of a KV lookup to populate a field only used in (uncommon)
// error messages is unwarranted.
// So instead, we mark the "database name as originally omitted"
// so as to prevent pretty-printing a potentially confusing empty
// database name in error messages (we want `foo` not `"".foo`).
DBNameOriginallyOmitted: true,
}
src, err := p.getPlanForDesc(ctx, desc, &tn, hints, scanVisibility, tref.Columns)
if err != nil {
return src, err
}
return renameSource(src, tref.As, true)
}
// renameSource applies an AS clause to a data source.
func renameSource(
src planDataSource, as parser.AliasClause, includeHidden bool,
) (planDataSource, error) {
var tableAlias parser.TableName
if as.Alias != "" {
// If an alias was specified, use that.
tableAlias.TableName = as.Alias
src.info.sourceAliases = sourceAliases{{
name: tableAlias,
columnRange: fillColumnRange(0, len(src.info.sourceColumns)-1),
}}
}
colAlias := as.Cols
if len(colAlias) > 0 {
// Make a copy of the slice since we are about to modify the contents.
src.info.sourceColumns = append(sqlbase.ResultColumns(nil), src.info.sourceColumns...)
// The column aliases can only refer to explicit columns.
for colIdx, aliasIdx := 0, 0; aliasIdx < len(colAlias); colIdx++ {
if colIdx >= len(src.info.sourceColumns) {
var srcName string
if tableAlias.DatabaseName != "" {
srcName = parser.ErrString(&tableAlias)
} else {
srcName = parser.ErrString(tableAlias.TableName)
}
return planDataSource{}, errors.Errorf(
"source %q has %d columns available but %d columns specified",
srcName, aliasIdx, len(colAlias))
}
if !includeHidden && src.info.sourceColumns[colIdx].Hidden {
continue
}
src.info.sourceColumns[colIdx].Name = string(colAlias[aliasIdx])
aliasIdx++
}
}
return src, nil
}
// getTableScanOrViewPlan builds a planDataSource from a single data source
// clause (either a table or a view) in a SelectClause, expanding views out
// into subqueries.
func (p *planner) getTableScanOrViewPlan(
ctx context.Context,
tn *parser.TableName,
hints *parser.IndexHints,
scanVisibility scanVisibility,
) (planDataSource, error) {
if tn.PrefixOriginallySpecified {
// Prefixes are currently only supported for virtual tables.
return planDataSource{}, parser.NewInvalidNameErrorf(
"invalid table name: %q", parser.ErrString(tn))
}
desc, err := p.getTableDesc(ctx, tn)
if err != nil {
return planDataSource{}, err
}
return p.getPlanForDesc(ctx, desc, tn, hints, scanVisibility, nil)
}
func (p *planner) getTableDesc(
ctx context.Context, tn *parser.TableName,
) (*sqlbase.TableDescriptor, error) {
if p.avoidCachedDescriptors {
// AS OF SYSTEM TIME queries need to fetch the table descriptor at the
// specified time, and never lease anything. The proto transaction already
// has its timestamps set correctly so getTableOrViewDesc will fetch with
// the correct timestamp.
return MustGetTableOrViewDesc(
ctx, p.txn, p.getVirtualTabler(), tn, false /*allowAdding*/)
}
return p.session.tables.getTableVersion(ctx, p.txn, p.getVirtualTabler(), tn)
}
func (p *planner) getPlanForDesc(
ctx context.Context,
desc *sqlbase.TableDescriptor,
tn *parser.TableName,
hints *parser.IndexHints,
scanVisibility scanVisibility,
wantedColumns []parser.ColumnID,
) (planDataSource, error) {
if desc.IsView() {
if wantedColumns != nil {
return planDataSource{},
errors.Errorf("cannot specify an explicit column list when accessing a view by reference")
}
return p.getViewPlan(ctx, tn, desc)
} else if !desc.IsTable() {
return planDataSource{}, errors.Errorf(
"unexpected table descriptor of type %s for %q", desc.TypeName(), parser.ErrString(tn))
}
// This name designates a real table.
scan := p.Scan()
if err := scan.initTable(p, desc, hints, scanVisibility, wantedColumns); err != nil {
return planDataSource{}, err
}
return planDataSource{
info: newSourceInfoForSingleTable(*tn, planColumns(scan)),
plan: scan,
}, nil
}
// getViewPlan builds a planDataSource for the view specified by the
// table name and descriptor, expanding out its subquery plan.
func (p *planner) getViewPlan(
ctx context.Context, tn *parser.TableName, desc *sqlbase.TableDescriptor,
) (planDataSource, error) {
stmt, err := parser.ParseOne(desc.ViewQuery)
if err != nil {
return planDataSource{}, errors.Wrapf(err, "failed to parse underlying query from view %q", tn)
}
sel, ok := stmt.(*parser.Select)
if !ok {
return planDataSource{},
errors.Errorf("failed to parse underlying query from view %q as a select", tn)
}
// When constructing the subquery plan, we don't want to check for the SELECT
// privilege on the underlying tables, just on the view itself. Checking on
// the underlying tables as well would defeat the purpose of having separate
// SELECT privileges on the view, which is intended to allow for exposing
// some subset of a restricted table's data to less privileged users.
if !p.skipSelectPrivilegeChecks {
if err := p.CheckPrivilege(desc, privilege.SELECT); err != nil {
return planDataSource{}, err
}
p.skipSelectPrivilegeChecks = true
defer func() { p.skipSelectPrivilegeChecks = false }()
}
// Register the dependency to the planner, if requested.
if p.planDeps != nil {
usedColumns := make([]sqlbase.ColumnID, len(desc.Columns))
for i := range desc.Columns {
usedColumns[i] = desc.Columns[i].ID
}
deps := p.planDeps[desc.ID]
deps.desc = desc
deps.deps = append(deps.deps, sqlbase.TableDescriptor_Reference{ColumnIDs: usedColumns})
p.planDeps[desc.ID] = deps
// We are only interested in the dependency to this view descriptor. Any
// further dependency by the view's query should not be tracked in this planner.
defer func(prev planDependencies) { p.planDeps = prev }(p.planDeps)
p.planDeps = nil
}
// TODO(a-robinson): Support ORDER BY and LIMIT in views. Is it as simple as
// just passing the entire select here or will inserting an ORDER BY in the
// middle of a query plan break things?
return p.getSubqueryPlan(ctx, *tn, sel.Select, sqlbase.ResultColumnsFromColDescs(desc.Columns))
}
// getSubqueryPlan builds a planDataSource for a select statement, including
// for simple VALUES statements.
func (p *planner) getSubqueryPlan(
ctx context.Context, tn parser.TableName, sel parser.SelectStatement, cols sqlbase.ResultColumns,
) (planDataSource, error) {
plan, err := p.newPlan(ctx, sel, nil)
if err != nil {
return planDataSource{}, err
}
if len(cols) == 0 {
cols = planColumns(plan)
}
return planDataSource{
info: newSourceInfoForSingleTable(tn, cols),
plan: plan,
}, nil
}
func (p *planner) getGeneratorPlan(
ctx context.Context, t *parser.FuncExpr,
) (planDataSource, error) {
plan, err := p.makeGenerator(ctx, t)
if err != nil {
return planDataSource{}, err
}
return planDataSource{
info: newSourceInfoForSingleTable(anonymousTable, planColumns(plan)),
plan: plan,
}, nil
}
// expandStar returns the array of column metadata and name
// expressions that correspond to the expansion of a star.
func (src *dataSourceInfo) expandStar(
v parser.VarName, ivarHelper parser.IndexedVarHelper,
) (columns sqlbase.ResultColumns, exprs []parser.TypedExpr, err error) {
if len(src.sourceColumns) == 0 {
return nil, nil, pgerror.NewErrorf(pgerror.CodeInvalidNameError,
"cannot use %q without a FROM clause", parser.ErrString(v))
}
colSel := func(idx int) {
col := src.sourceColumns[idx]
if !col.Hidden {
ivar := ivarHelper.IndexedVar(idx)
columns = append(columns, sqlbase.ResultColumn{Name: col.Name, Typ: ivar.ResolvedType()})
exprs = append(exprs, ivar)
}
}
tableName := parser.TableName{DBNameOriginallyOmitted: true}
if a, ok := v.(*parser.AllColumnsSelector); ok {
tableName = a.TableName
}
if tableName.Table() == "" {
for i := 0; i < len(src.sourceColumns); i++ {
colSel(i)
}
} else {
qualifiedTn, err := src.checkDatabaseName(tableName)
if err != nil {
return nil, nil, err
}
colRange, ok := src.sourceAliases.columnRange(qualifiedTn)
if !ok {
return nil, nil, sqlbase.NewUndefinedRelationError(&tableName)
}
for _, i := range colRange {
colSel(i)
}
}
return columns, exprs, nil
}
type multiSourceInfo []*dataSourceInfo
func newUnknownSourceError(tn *parser.TableName) error {
return pgerror.NewErrorf(pgerror.CodeUndefinedTableError,
"source name %q not found in FROM clause", parser.ErrString(tn))
}
func newAmbiguousSourceError(t parser.Name, dbContext parser.Name) error {
if dbContext == "" {
return pgerror.NewErrorf(pgerror.CodeAmbiguousAliasError,
"ambiguous source name: %q", parser.ErrString(t))
}
return pgerror.NewErrorf(pgerror.CodeAmbiguousAliasError,
"ambiguous source name: %q (within database %q)",
parser.ErrString(t), parser.ErrString(dbContext))
}
// checkDatabaseName checks whether the given TableName is unambiguous
// for the set of sources and if it is, qualifies the missing database name.
func (sources multiSourceInfo) checkDatabaseName(tn parser.TableName) (parser.TableName, error) {
if tn.DatabaseName == "" {
// No database name yet. Try to find one.
found := false
for _, src := range sources {
for _, alias := range src.sourceAliases {
if alias.name.TableName == tn.TableName {
if found {
return parser.TableName{}, newAmbiguousSourceError(tn.TableName, "")
}
tn.DatabaseName = alias.name.DatabaseName
found = true
}
}
}
if !found {
return parser.TableName{}, newUnknownSourceError(&tn)
}
return tn, nil
}
// Database given. Check that the name is unambiguous.
found := false
for _, src := range sources {
if _, ok := src.sourceAliases.srcIdx(tn); ok {
if found {
return parser.TableName{}, newAmbiguousSourceError(tn.TableName, tn.DatabaseName)
}
found = true
}
}
if !found {
return parser.TableName{}, newUnknownSourceError(&tn)
}
return tn, nil
}
// checkDatabaseName checks whether the given TableName is unambiguous
// within this source and if it is, qualifies the missing database name.
func (src *dataSourceInfo) checkDatabaseName(tn parser.TableName) (parser.TableName, error) {
if tn.DatabaseName == "" {
// No database name yet. Try to find one.
found := false
for _, alias := range src.sourceAliases {
if alias.name.TableName == tn.TableName {
if found {
return parser.TableName{}, newAmbiguousSourceError(tn.TableName, "")
}
found = true
tn.DatabaseName = alias.name.DatabaseName
}
}
if !found {
return parser.TableName{}, newUnknownSourceError(&tn)
}
return tn, nil
}
// Database given.
if _, found := src.sourceAliases.srcIdx(tn); !found {
return parser.TableName{}, newUnknownSourceError(&tn)
}
return tn, nil
}
// findColumn looks up the column specified by a ColumnItem. The
// function returns the index of the source in the multiSourceInfo
// array and the column index for the column array of that
// source. Returns invalid indices and an error if the source is not
// found or the name is ambiguous.
func (sources multiSourceInfo) findColumn(
c *parser.ColumnItem,
) (srcIdx int, colIdx int, err error) {
if len(c.Selector) > 0 {
return invalidSrcIdx, invalidColIdx, pgerror.UnimplementedWithIssueErrorf(8318, "compound types not supported yet: %q", c)
}
colName := string(c.ColumnName)
var tableName parser.TableName
if c.TableName.Table() != "" {
tn, err := sources.checkDatabaseName(c.TableName)
if err != nil {
return invalidSrcIdx, invalidColIdx, err
}
tableName = tn
// Propagate the discovered database name back to the original VarName.
// (to clarify the output of e.g. EXPLAIN)
c.TableName.DatabaseName = tableName.DatabaseName
}
findColHelper := func(src *dataSourceInfo, iSrc, srcIdx, colIdx int, idx int) (int, int, error) {
col := src.sourceColumns[idx]
if col.Name == colName {
if colIdx != invalidColIdx {
return invalidSrcIdx, invalidColIdx, pgerror.NewErrorf(pgerror.CodeAmbiguousColumnError,
"column reference %q is ambiguous", parser.ErrString(c))
}
srcIdx = iSrc
colIdx = idx
}
return srcIdx, colIdx, nil
}
colIdx = invalidColIdx
for iSrc, src := range sources {
colRange, ok := src.sourceAliases.columnRange(tableName)
if !ok {
// The data source "src" has no column for table tableName.
// Try again with the net one.
continue
}
for _, idx := range colRange {
srcIdx, colIdx, err = findColHelper(src, iSrc, srcIdx, colIdx, idx)
if err != nil {
return srcIdx, colIdx, err
}
}
}
if colIdx == invalidColIdx && tableName.Table() == "" {
// Try harder: unqualified column names can look at all
// columns, not just columns of the anonymous table.
for iSrc, src := range sources {
for idx := 0; idx < len(src.sourceColumns); idx++ {
srcIdx, colIdx, err = findColHelper(src, iSrc, srcIdx, colIdx, idx)
if err != nil {
return srcIdx, colIdx, err
}
}
}
}
if colIdx == invalidColIdx {
return invalidSrcIdx, invalidColIdx,
pgerror.NewErrorf(pgerror.CodeUndefinedColumnError,
"column name %q not found", parser.ErrString(c))
}
return srcIdx, colIdx, nil
}
// findTableAlias returns the first table alias providing the column
// index given as argument. The index must be valid.
func (src *dataSourceInfo) findTableAlias(colIdx int) (parser.TableName, bool) {
for _, alias := range src.sourceAliases {
for _, idx := range alias.columnRange {
if colIdx == idx {
return alias.name, true
}
}
}
return anonymousTable, false
}
func (src *dataSourceInfo) FormatVar(buf *bytes.Buffer, f parser.FmtFlags, colIdx int) {
if f.ShowTableAliases {
tableAlias, found := src.findTableAlias(colIdx)
if found {
if tableAlias.TableName != "" {
if tableAlias.DatabaseName != "" {
parser.FormatNode(buf, f, tableAlias.DatabaseName)
buf.WriteByte('.')
}
parser.FormatNode(buf, f, tableAlias.TableName)
buf.WriteByte('.')
}
} else {
buf.WriteString("_.")
}
}
parser.Name(src.sourceColumns[colIdx].Name).Format(buf, f)
}