fast sort

[Keith E. Black]

This is a simple bubble sort. How can I make it sort faster.

'*******************************************
Changed% = 0
FOR c% = 2 TO Matches%
SEEK #OutFile%, ((c% - 2) * %QueryLen) + Offset%(KeyField%)
GET$ #OutFile%, FldLen%(KeyField%), Buffer1$
SEEK #OutFile%, ((c% - 1) * %QueryLen) + Offset%(KeyField%)
GET$ #OutFile%, FldLen%(KeyField%), Buffer2$
IF ucASE$(Buffer1$) > UCASE$(Buffer2$) THEN ' we need to swap these records
Changed% = -1 ' we've made a change, so we'll have to make another pass through the file
SEEK #OutFile%, (c% - 2) * %QueryLen
GET #OutFile%, , Record1
GET #OutFile%, , Record2
' swap the records
SEEK #OutFile%, (c% - 2) * %QueryLen
PUT #OutFile%, , Record2
PUT #OutFile%, , Record1
END IF
NEXT c%
LOOP WHILE Changed%
' the file is now sorted, so print the report

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[Michael Mattias]

One fast suggestion: if the file can be loaded into a non-HUGE array, load it and do the swapping in memory rather than "in-place" on disk. Put the array back on disk when sorted.

Depending on keysize and recordsize, it may work out better to load only an index, sort that and then put the records back into a new file.

Or, you can change sort algorithms. I have PB/DOS code for an 'inplace' disk sort; I also have code for PB/DOS to sort a HUGE array.

What recordsize, number of records and keylength are you looking at? The best design will be dependent on that.

MCM

[Mark Hunter]

if what michael suggests is possible, you could
use the tag feature of array sort to sort the
index and have what it points to "tag" along.

even faster is my code you will find at http://www.powerbasic.com/support/pb...ad.php?t=18757

[David J Walker]

Sort both up and down, decrementing the top limit and incrementing the bottom limit on each pass.
I call this the Bubble and Brick sort.

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[Mark Hunter]

The bubble sort compares and swaps consecutive pairs,
passing through the entire list repeatedly until no swap
is necessary.

For this procedure to sort the list, the list must be
scanned top to bottom on each pass.