Re: [Harbour] DBSEEK()
On Tue, 29 Dec 2009, Mindaugas Kavaliauskas wrote:
Hi,
It's defined indirectly by dynamic descend flag which causes
that seek last should work like in Harbour native RDDs and
CL53/COMIX. In such implementation seek last is fully revertible
by switching to descending order ( ordDescend(,,!ordDescend()) )
and forward seek. Otherwise we will have some anomalies.
Ok, if understand the idea of seeklast now, then it means try doing
seek backward (in reversed index order, like using DESCEND), but
not return the last record (having maximal recno value) of the
records having the same key value.
Too much complicated for me ;-)
I rather suggest you to think about functionality. This code:
dbSeek( dtFirst, .T., .F. )
while field-DATE = dtLast .and. !EOF()
[...]
dbSkip( 1 )
enddo
should scan the same record set as this code:
dbSeek( dtLast, .T., .T. )
while field-DATE = dtFirst .and. !BOF()
[...]
dbSkip( -1 )
enddo
and this also precisely defines which record should be chosen
when the exact key does not exists and for soft seek last.
But ADS still have bug in the first test. If softseek positions at
EOF seeklast does not help to stop on last record. Here is the test
indicating both correct (in some cases) and wrong (in another cases)
behavior of ADS:
Yes, and your patch is correct though probably we can remove
AdsAtEOF() checking and always call:
u32RetVal = AdsSkip( pArea-hOrdCurrent, -1 );
I also suggest to store in u32RetVal AdsSeek() and AdsSeekLast() results
and move:
if( u32RetVal != AE_SUCCESS )
{
commonError( pArea, EG_CORRUPTION, ( HB_ERRCODE ) u32RetVal, 0, NULL,
EF_CANDEFAULT, NULL );
return HB_FAILURE;
}
to always generate RTE also when AdsSeek*() fails.
Please only check the AdsSeek*() results for empty ADT and DBF tables.
best regards,
Przemek
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[Harbour] DBSEEK()
Hello,
I have a question/discussion about DBSEEK(). I've started from the
different ADSCDX and DBFCDX behavior and later included Clipper tests.
#ifdef __HARBOUR__
REQUEST ADSCDX
#endif
REQUEST DBFCDX
FIELD F
FUNC main(cADS)
IF EMPTY(cADS)
RDDSETDEFAULT(DBFCDX)
ELSE
RDDSETDEFAULT(ADSCDX)
ENDIF
? VERSION(), RDDSETDEFAULT()
DBCREATE(test187, {{F, N, 5, 0}},, .T.)
OrdCreate(test187, f, F)
DBAPPEND(); F := 1
DBSEEK(10, .T., .F.)
? RECNO()
DBSEEK(10, .T., .T.)
? RECNO()
DBCLOSEALL()
RETURN 0
The code above prints:
C:\cawi32\sample\testtest187.exe
Harbour 2.0.0 (Rev. 13372) DBFCDX
2
1
C:\cawi32\sample\testtest187.exe xxx
Harbour 2.0.0 (Rev. 13372) ADSCDX
2
2
C:\cawi32\sample\testtest187.exe
Clipper (R) 5.2e Intl. (x216) (1995.02.07) DBFCDX
2
2
So, I looks like Harbour's DBFCDX is wrong and ADSCDX is OK, but my
co-worker said, that Clipper has bugs in softseek. I've tried another test:
REQUEST DBFCDX
#ifdef __HARBOUR__
REQUEST ADSCDX
#endif
FIELD F
PROC main(cADS)
IF EMPTY(cADS)
RDDSETDEFAULT(DBFCDX)
ELSE
RDDSETDEFAULT(ADSCDX)
ENDIF
? VERSION(), RDDSETDEFAULT()
DBCREATE(test188, {{F, N, 5, 0}},, .T.)
OrdCreate(test188, f, F)
DBAPPEND(); F := 1
DBAPPEND(); F := 1
DBAPPEND(); F := 3
DBAPPEND(); F := 3
DBSEEK(2, .T., .F.)
? RECNO()
DBSEEK(2, .T., .T.)
? RECNO()
DBCLOSEALL()
RETURN
It prints:
C:\cawi32\sample\testtest188.exe
Harbour 2.0.0 (Rev. 13372) DBFCDX
3
2
C:\cawi32\sample\testtest188.exe xxx
Harbour 2.0.0 (Rev. 13372) ADSCDX
2
2
C:\cawi32\sample\testtest188.exe
Clipper (R) 5.2e Intl. (x216) (1995.02.07) DBFCDX
5
5
So, we have a different behavior for all of RDD's, and I seems Clipper
ignores softseek at all.
From a printed (CL53) reference guide vol.1 page 2-315 I can read:
lLast is specified as true (.T.) to seek the last occurence of the
specified key value. , but it is not clear how it works if specified
key does not exists. I can also read on the same page: ... for a soft
seek, the work area is positioned to the first record whose key value is
greater than the specified key value. If no such record exists, the work
area is positioned to LASTREC() + 1 and EOF() returns true (.T.).
So, in the latter sample (test188) I would expect:
3
4
but not any of the above results from various tests.
*** So, how soft seek and last seek should work? ***
The question becomes even more complicated if think about DESCENT index.
Regards,
Mindaugas
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Re: [Harbour] DBSEEK()
Hi, Przemek,
I've made fixed in my SVN copy, but I see you comment in ADSRDD code
related to the subject, so, please verify, that fix is OK.
Index: C:/harbour/contrib/rddads/ads1.c
===
--- C:/harbour/contrib/rddads/ads1.c(revision 13378)
+++ C:/harbour/contrib/rddads/ads1.c(working copy)
@@ -1072,13 +1072,14 @@
AdsAtEOF( pArea-hTable, u16Eof );
if( !u16Eof )
+u32RetVal = AdsSkip( pArea-hOrdCurrent, -1 );
+ else
+u32RetVal = AdsGotoBottom( pArea-hOrdCurrent );
+
+ if( u32RetVal != AE_SUCCESS )
{
-u32RetVal = AdsSkip( pArea-hOrdCurrent, -1 );
-if( u32RetVal != AE_SUCCESS )
-{
- commonError( pArea, EG_CORRUPTION, ( HB_ERRCODE )
u32RetVal, 0, NULL, EF_CANDEFAULT, NULL );
- return HB_FAILURE;
-}
+commonError( pArea, EG_CORRUPTION, ( HB_ERRCODE )
u32RetVal, 0, NULL, EF_CANDEFAULT, NULL );
+return HB_FAILURE;
}
}
}
I also attach extended test code. It includes also test for the
seeksoft/seeklast in the beginning of index.
Regards,
Mindaugas
REQUEST DBFCDX
#ifdef __HARBOUR__
REQUEST ADSCDX
#endif
FIELD F
PROC main(cADS, cLocal)
IF EMPTY(cADS)
RDDSETDEFAULT(DBFCDX)
ELSE
#ifdef __HARBOUR__
RDDSETDEFAULT(ADSCDX)
AdsSetServerType(IIF(EMPTY(cLocal), 2, 1))
#endif
ENDIF
? VERSION(), RDDSETDEFAULT()
DBCREATE(test188, {{F, N, 5, 0}},, .T.)
OrdCreate(test188, f, F, {|| F})
DBAPPEND(); F := 1
DBAPPEND(); F := 1
DBAPPEND(); F := 3
DBAPPEND(); F := 3
DBSEEK(2, .T., .F.); ? RECNO()
DBSEEK(2, .T., .T.); ? RECNO()
DBSEEK(9, .T., .F.); ? RECNO()
DBSEEK(9, .T., .T.); ? RECNO()
DBSEEK(0, .T., .F.); ? RECNO()
DBSEEK(0, .T., .T.); ? RECNO()
DBCLOSEALL()
RETURN
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[Harbour] DbSeek() Problem with latest SVN
Hi Przemek, I had encountered problem with the latest SVN with DbSeek(). It always return .F. in my case after reindexing and re-creating index. I'm using DBFNTX and BCC62 under WinXP SP3. Thanks for any advise. Best regards, Mario ___ Harbour mailing list Harbour@harbour-project.org http://lists.harbour-project.org/mailman/listinfo/harbour
