Re: [sqlite] sorting of blobs
Well done, you have answered the man's question. Joe Wilson wrote: --- John Stanton <[EMAIL PROTECTED]> wrote: Try looking at the SORT opcode. You can track it through the Sqlite source. OP_Sort doesn't sort any longer. It just does a rewind on the cursor. /* Opcode: Sort P1 P2 * ** ** This opcode does exactly the same thing as OP_Rewind except that ** it increments an undocumented global variable used for testing. ** ** Sorting is accomplished by writing records into a sorting index, ** then rewinding that index and playing it back from beginning to ** end. We use the OP_Sort opcode instead of OP_Rewind to do the ** rewinding so that the global variable will be incremented and ** regression tests can determine whether or not the optimizer is ** correctly optimizing out sorts. */ Shape Yahoo! in your own image. Join our Network Research Panel today! http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7 - To unsubscribe, send email to [EMAIL PROTECTED] - - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] sorting of blobs
--- John Stanton <[EMAIL PROTECTED]> wrote: > Try looking at the SORT opcode. You can track it through the Sqlite source. OP_Sort doesn't sort any longer. It just does a rewind on the cursor. /* Opcode: Sort P1 P2 * ** ** This opcode does exactly the same thing as OP_Rewind except that ** it increments an undocumented global variable used for testing. ** ** Sorting is accomplished by writing records into a sorting index, ** then rewinding that index and playing it back from beginning to ** end. We use the OP_Sort opcode instead of OP_Rewind to do the ** rewinding so that the global variable will be incremented and ** regression tests can determine whether or not the optimizer is ** correctly optimizing out sorts. */ Shape Yahoo! in your own image. Join our Network Research Panel today! http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7 - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] sorting of blobs
B V, Phanisekhar wrote: Assume I have an albumtable: create table albumtable (albumid INTEGER PRIMARY KEY, album BLOB); Now I do a query to return the entire albums in the albumtable table in alphabetical order: The instructions for the above query are given below: explain select album from albumtable order by album; addr opcode p1 p2 p3 -- -- -- - 0 OpenEphemeral 1 3 keyinfo(1,BINARY) 1 Goto0 26 2 Integer 0 0 3 OpenRead0 2 4 SetNumColumns 0 2 5 Rewind 0 14 6 Column 0 1 7 MakeRecord 1 0 8 Column 0 1 9 Sequence1 0 10Pull2 0 11MakeRecord 3 0 12IdxInsert 1 0 13Next0 6 14Close 0 0 15OpenPseudo 2 0 16SetNumColumns 2 1 17Sort1 24 18Integer 1 0 19Column 1 2 20Insert 2 0 21Column 2 0 22Callback1 0 23Next1 18 24Close 2 0 25Halt0 0 26Transaction 0 0 27VerifyCookie0 1 28Goto0 2 29Noop0 0 I would like to know which portion of the above code does the sorting of the blobs "album". Basically would like to know where exactly the comparison "album A > album B" is done. Regards, Phanisekhar Try looking at the SORT opcode. You can track it through the Sqlite source. - To unsubscribe, send email to [EMAIL PROTECTED] -
Re: [sqlite] sorting of blobs
On Wed, 2007-07-18 at 16:03 +0530, B V, Phanisekhar wrote: > Assume I have an albumtable: > > create table albumtable (albumid INTEGER PRIMARY KEY, album BLOB); > > > > Now I do a query to return the entire albums in the albumtable table in > alphabetical order: > > > > The instructions for the above query are given below: > > > > explain select album from albumtable order by album; > > > > addr opcode p1 p2 p3 > > -- -- -- > - > > 0 OpenEphemeral 1 3 keyinfo(1,BINARY) > > 1 Goto0 26 > > 2 Integer 0 0 > > 3 OpenRead0 2 > > 4 SetNumColumns 0 2 > > 5 Rewind 0 14 > > 6 Column 0 1 > > 7 MakeRecord 1 0 > > 8 Column 0 1 > > 9 Sequence1 0 > > 10Pull2 0 > > 11MakeRecord 3 0 > > 12IdxInsert 1 0 > > 13Next0 6 > > 14Close 0 0 > > 15OpenPseudo 2 0 > > 16SetNumColumns 2 1 > > 17Sort1 24 > > 18Integer 1 0 > > 19Column 1 2 > > 20Insert 2 0 > > 21Column 2 0 > > 22Callback1 0 > > 23Next1 18 > > 24Close 2 0 > > 25Halt0 0 > > 26Transaction 0 0 > > 27VerifyCookie0 1 > > 28Goto0 2 > > 29Noop0 0 > > > > I would like to know which portion of the above code does the sorting of > the blobs "album". > > Basically would like to know where exactly the comparison "album A > > album B" is done. Instructions 6-13 are a loop inserting rows into a temporary b-tree structure. The value of the "album" column is used as the key for this table. Instructions 17-23 iterate through this table, pulling records out in sorted order. So the comparison is done in instruction 12. Dan. > > > > Regards, > > Phanisekhar > > > > > > > > > - To unsubscribe, send email to [EMAIL PROTECTED] -
[sqlite] sorting of blobs
Assume I have an albumtable: create table albumtable (albumid INTEGER PRIMARY KEY, album BLOB); Now I do a query to return the entire albums in the albumtable table in alphabetical order: The instructions for the above query are given below: explain select album from albumtable order by album; addr opcode p1 p2 p3 -- -- -- - 0 OpenEphemeral 1 3 keyinfo(1,BINARY) 1 Goto0 26 2 Integer 0 0 3 OpenRead0 2 4 SetNumColumns 0 2 5 Rewind 0 14 6 Column 0 1 7 MakeRecord 1 0 8 Column 0 1 9 Sequence1 0 10Pull2 0 11MakeRecord 3 0 12IdxInsert 1 0 13Next0 6 14Close 0 0 15OpenPseudo 2 0 16SetNumColumns 2 1 17Sort1 24 18Integer 1 0 19Column 1 2 20Insert 2 0 21Column 2 0 22Callback1 0 23Next1 18 24Close 2 0 25Halt0 0 26Transaction 0 0 27VerifyCookie0 1 28Goto0 2 29Noop0 0 I would like to know which portion of the above code does the sorting of the blobs "album". Basically would like to know where exactly the comparison "album A > album B" is done. Regards, Phanisekhar
