Commented by: Sean Leyne (seanleyne)

Please post a sample to allow for the case to be confirmed. Otherwise, this case will be closed as not-reproducible.

Commented by: Montri Patchaiyo (k1)

This is a simple test case:

First:
CREATE TABLE TB_MENUS (
RECORD_ID INTEGER,
PARENT_ID INTEGER,
ORDER_ITEM INTEGER NOT NULL,
MENU_NAME VARCHAR(120),
APP_NAME VARCHAR(80),
MENU_ICON BLOB SUB_TYPE 0 SEGMENT SIZE 80
);

Second:
INSERT INTO TB_MENUS (0, NULL, 1, 'M1', NULL, NULL);
INSERT INTO TB_MENUS (1, 0, 1, 'M1 - Sub1', 'APP1.EXE', NULL);
INSERT INTO TB_MENUS (2, 0, 1, 'M1 - Sub2', 'APP2.EXE', NULL);

Last: execute following statement
WITH RECURSIVE
MENUS_LIST AS (
SELECT
PARENT_ID,
RECORD_ID,
ORDER_ITEM,
MENU_NAME,
APP_NAME,
MENU_ICON,
CAST('' AS VARCHAR(255)) IDENT
FROM
TB_MENUS
WHERE
(PARENT_ID IS NULL)

UNION ALL

SELECT
  M\.PARENT\_ID,
  M\.RECORD\_ID,
  M\.ORDER\_ITEM,
  M\.MENU\_NAME,
  M\.APP\_NAME,
  MENU\_ICON,
  H\.IDENT \|\| '    ' IDENT
FROM
  TB\_MENUS M INNER JOIN MENUS\_LIST H
  ON \(M\.PARENT\_ID = H\.RECORD\_ID\)

)
SELECT
PARENT_ID,
RECORD_ID,
ORDER_ITEM,
(IDENT || MENU_NAME) "Menu Name",
APP_NAME,
MENU_ICON,
FROM
MENUS_LIST

Even if you try to update or insert any values for MENU_ICON fields, the error was occured with message "Error writing data to the connection".
The error is occured if table is still has a values for a BLOB fields and has effected only for recursive one.

Commented by: @hvlad

The bug is not related with CTE. It can be reproduced much simpler :

SELECT MENU_ICON
FROM TB_MENUS

UNION ALL

SELECT MENU_ICON
FROM TB_MENUS

this also leads to AV in BLB_move. But it is worked well in FB 2.0

I think bug was introduced in FB 2.1 when text operations on blobs was implemented. Look at EXE_assignment :

in 2.0 it does

#⁠ifndef VMS
if (DTYPE_IS_BLOB(to_desc->dsc_dtype))
#⁠else
if (DTYPE_IS_BLOB(to_desc->dsc_dtype)
&& to_desc->dsc_dtype != dtype_d_float)
#⁠endif
BLB_move(tdbb, from_desc, to_desc, to);

	else if \(\!DSC\_EQUIV\(from\_desc, to\_desc, false\)\)
		MOV\_move\(from\_desc, to\_desc\);

in 2.1 it does

	if \(DTYPE\_IS\_BLOB\_OR\_QUAD\(from\_desc\-\>dsc\_dtype\) \|\|
		DTYPE\_IS\_BLOB\_OR\_QUAD\(to\_desc\-\>dsc\_dtype\)\)
	\{
		BLB\_move\(tdbb, from\_desc, to\_desc, to\);
	\}

Note - we have source type dtype_blob and target type dtype_quad as we want to assign blob_id (not to create new blob!)

So - FB 2.0 call MOV_move but FB 2.1 call BLB_move which failed getting target record relation (which is NULL in this case of course)

Commented by: @pcisar

Test added, but can't confirm the fix for 2.1 Alpha 1. Test fails with lost connection to the database. I suppose it's because it was fixed after Alpha 1, but then you need to assign correct fix version.

Commented by: @dyemanov

Pavel, some tests can fail due to a bug in the "lazy packet send" implementation of Alpha 1. It shows itself as a lost connection without crashes on any side. It affects TCP and NetBEUI connections only, so you could try writing the test using a local connection string. Or just use a fresh snapshot build :-)

Commented by: @pcisar

Fix verified, test added.