Implement https://sqlite.org/c3ref/vtab_in.html #126
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| Original file line number | Diff line number | Diff line change | ||||||||||||
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@@ -252,14 +252,17 @@ func (outputs *IndexOutputs) copyToC(tls *libc.TLS, infoPtr uintptr) error { | |||||||||||||
| info := (*lib.Sqlite3_index_info)(unsafe.Pointer(infoPtr)) | ||||||||||||||
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| aConstraintUsage := info.FaConstraintUsage | ||||||||||||||
| for i, u := range outputs.ConstraintUsage { | ||||||||||||||
| ptr := (*lib.Sqlite3_index_constraint_usage)(unsafe.Pointer(aConstraintUsage)) | ||||||||||||||
| ptr.FargvIndex = int32(u.ArgvIndex) | ||||||||||||||
| if u.Omit { | ||||||||||||||
| ptr.Fomit = 1 | ||||||||||||||
| } else { | ||||||||||||||
| ptr.Fomit = 0 | ||||||||||||||
| } | ||||||||||||||
| if u.InOpAllAtOnce { | ||||||||||||||
| lib.Xsqlite3_vtab_in(tls, infoPtr, int32(i), 1) | ||||||||||||||
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There was a problem hiding this comment. Perhaps check the return value of this? IIUC if it's zero, that indicates that the library user has improperly used this call. |
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| } | ||||||||||||||
| aConstraintUsage += unsafe.Sizeof(lib.Sqlite3_index_constraint_usage{}) | ||||||||||||||
| } | ||||||||||||||
| info.FidxNum = outputs.ID.Num | ||||||||||||||
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@@ -306,6 +309,9 @@ type IndexConstraintUsage struct { | |||||||||||||
| // SQLite will always double-check that rows satisfy the constraint if Omit is false, | ||||||||||||||
| // but may skip this check if Omit is true. | ||||||||||||||
| Omit bool | ||||||||||||||
| // Set InOpAllAtOnce to true if the constraint is an IN operator and the | ||||||||||||||
| // Filter method should receive all values at once. | ||||||||||||||
| InOpAllAtOnce bool | ||||||||||||||
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Comment on lines
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There was a problem hiding this comment. nit: We abbreviate operator for common usages, but this is less common, so let's spell it out here.
Suggested change
The doc comment should also include instructions on how to access the values. |
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| } | ||||||||||||||
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| // IndexID is a virtual table index identifier. | ||||||||||||||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -38,6 +38,19 @@ func ExampleVTable() { | |
| log.Fatal(err) | ||
| } | ||
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| err = sqlitex.ExecuteTransient( | ||
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There was a problem hiding this comment. This doesn't feel like something that needs to be included in an introductory example. IIUC SQLite will fall back to a simpler set of indices and still operate without this. It definitely still needs testing, but shouldn't be in this example. |
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| conn, | ||
| `SELECT a, b FROM templatevtab WHERE a IN (1001, 1003, 1005, 1007, 1009) ORDER BY rowid;`, | ||
| &sqlitex.ExecOptions{ | ||
| ResultFunc: func(stmt *sqlite.Stmt) error { | ||
| fmt.Printf("%4d, %4d\n", stmt.ColumnInt(0), stmt.ColumnInt(1)) | ||
| return nil | ||
| }, | ||
| }, | ||
| ) | ||
| if err != nil { | ||
| log.Fatal(err) | ||
| } | ||
| // Output: | ||
| // 1001, 2001 | ||
| // 1002, 2002 | ||
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@@ -49,6 +62,11 @@ func ExampleVTable() { | |
| // 1008, 2008 | ||
| // 1009, 2009 | ||
| // 1010, 2010 | ||
| // 1001, 2001 | ||
| // 1003, 2003 | ||
| // 1005, 2005 | ||
| // 1007, 2007 | ||
| // 1009, 2009 | ||
| } | ||
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| type templatevtab struct{} | ||
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@@ -66,10 +84,22 @@ func templatevtabConnect(c *sqlite.Conn, opts *sqlite.VTableConnectOptions) (sql | |
| return vtab, cfg, nil | ||
| } | ||
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| func (vt *templatevtab) BestIndex(in *sqlite.IndexInputs) (*sqlite.IndexOutputs, error) { | ||
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| constraintUsage := make([]sqlite.IndexConstraintUsage, len(in.Constraints)) | ||
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| argvIndex := 1 | ||
| for i, c := range in.Constraints { | ||
| if c.InOpAllAtOnce { | ||
| constraintUsage[i].ArgvIndex = argvIndex | ||
| constraintUsage[i].InOpAllAtOnce = true | ||
| argvIndex++ | ||
| } | ||
| } | ||
| return &sqlite.IndexOutputs{ | ||
| ConstraintUsage: constraintUsage, | ||
| EstimatedCost: 10, | ||
| EstimatedRows: 10, | ||
| }, nil | ||
| } | ||
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@@ -86,10 +116,17 @@ func (vt *templatevtab) Destroy() error { | |
| } | ||
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| type templatevtabCursor struct { | ||
| rowid int64 | ||
| inVals []int64 | ||
| } | ||
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| func (cur *templatevtabCursor) Filter(id sqlite.IndexID, argv []sqlite.Value) error { | ||
| for _, v := range argv { | ||
| for vv := range v.All() { | ||
| cur.inVals = append(cur.inVals, vv.Int64()) | ||
| } | ||
| } | ||
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| cur.rowid = 1 | ||
| return nil | ||
| } | ||
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@@ -102,8 +139,14 @@ func (cur *templatevtabCursor) Next() error { | |
| func (cur *templatevtabCursor) Column(i int, noChange bool) (sqlite.Value, error) { | ||
| switch i { | ||
| case templatevarColumnA: | ||
| if len(cur.inVals) > 0 { | ||
| return sqlite.IntegerValue(cur.inVals[cur.rowid-1]), nil | ||
| } | ||
| return sqlite.IntegerValue(1000 + cur.rowid), nil | ||
| case templatevarColumnB: | ||
| if len(cur.inVals) > 0 { | ||
| return sqlite.IntegerValue(1000 + cur.inVals[cur.rowid-1]), nil | ||
| } | ||
| return sqlite.IntegerValue(2000 + cur.rowid), nil | ||
| default: | ||
| panic("unreachable") | ||
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@@ -115,6 +158,9 @@ func (cur *templatevtabCursor) RowID() (int64, error) { | |
| } | ||
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| func (cur *templatevtabCursor) EOF() bool { | ||
| if len(cur.inVals) > 0 { | ||
| return int(cur.rowid) > len(cur.inVals) | ||
| } | ||
| return cur.rowid > 10 | ||
| } | ||
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While I appreciate the simplicity of the iterator interface, I'm not quite sold on this API for a few reasons:
Valueobjects from these functions is somewhat tricky and that complexity is not being surfaced to the user.I don't have a great counter-proposal for this design, but I didn't want to block the feedback on me coming up with something.
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Yeah good points. What if this were a method on the VTCursor interface instead? Then it would be much harder to use outside the Filter function (the only place
sqlite_vtab_in_{first,next}are valid to use).Also do you think the golang iter interface is ok or passing in a callback function is preferred?