rereadnolock causes non-forward-only query to read first tab

Posted by cverbiest on 25-Jul-2019 07:56

Following sample demonstrates the issue.

In a session with -rereadnolock the number of records read from the first table is double the number of records available in the table.

find _file where _file._file-name = "customer" no-lock.
find _tablestat where _file._file-number = _tablestat._tablestat-id no-lock.

def var qh as handle.
def var count as int.
def var startread as int.

startread = _tablestat._tablestat-read.
create query qh .
qh:forward-only = false.
qh:set-buffers(buffer customer:handle, buffer salesrep:handle).
qh:query-prepare("for each customer, first salesrep of customer").
qh:query-open().
do while qh:get-next(): count = count + 1. end.
qh:query-close().
find _tablestat where _file._file-number = _tablestat._tablestat-id no-lock.
disp count startread _tablestat._tablestat-read _tablestat._tablestat-read - startread label "diff" with no-box side-labels.

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Posted by George Potemkin on 26-Jul-2019 07:58

Off-topic note:

> find _tablestat where _file._file-number = _tablestat._tablestat-id no-lock.

The code works as expected with any value of -basetable only since version 11.7 (mayby 11.7 something).

DISPLAY PROVERSION(1) "Wait...".
FOR FIRST _StatBase EXCLUSIVE-LOCK:
  ASSIGN _TableBase = 2.
END.

FIND FIRST _TableStat NO-LOCK WHERE _TableStat-Id EQ 2.
DISPLAY _TableStat-Id.

The code above will show "3" in versions before 11.7 and "2" in version 11.7.

DISPLAY PROVERSION(1) "Wait...".
FOR FIRST _DbParams EXCLUSIVE-LOCK WHERE _DbParams-Name EQ "-basetable":U:
  ASSIGN  _DbParams._DbParams-Value = "2":U.
END.

FIND FIRST _TableStat NO-LOCK WHERE _TableStat-Id EQ 2.
DISPLAY _TableStat-Id.

This code shows "2" in version 12.0.

Posted by Rob Fitzpatrick on 26-Jul-2019 13:23

> The code works as expected with any value of -basetable only since version 11.7 (mayby 11.7 something).

This was fixed in 11.7.0.

pugchallenge.org/.../New_VSTs.pdf

"OE 11.7.0 fixed VSI for base != 1"

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