# Block Transaction DB to OPC no write if DB table & PLC size are not the same **URL:** \ **Category:** Ignition\ **Tags:** ignition80, database\ **Created:** [April 4, 2020, 3:26pm UTC](https://forum.inductiveautomation.com/t/block-transaction-db-to-opc-no-write-if-db-table-plc-size-are-not-the-same/33685 "2020-04-04T15:26:31Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![jlandwerlen](https://avatars.discourse-cdn.com/v4/letter/j/bc8723/32.png) [@jlandwerlen](https://forum.inductiveautomation.com/u/jlandwerlen)\ **Post date:** [April 4, 2020, 3:26pm UTC](https://forum.inductiveautomation.com/t/block-transaction-db-to-opc-no-write-if-db-table-plc-size-are-not-the-same/33685/1 "2020-04-04T15:26:32Z")
Using v.8.0.10, I have a view in MySQL, currently it returns 8 rows. I have a block transaction group that is DB to OPC, the OPC data size is 20. If I set the transaction group size/length to anything larger than the view row length, no OPC writes will occur. No errors, just no writes. Once I change the size/length to 8, it will start writing. Is this normal behavior? ---
**Author:** ![danFromNj](https://avatars.discourse-cdn.com/v4/letter/d/76d3ee/32.png) [@danFromNj](https://forum.inductiveautomation.com/u/danFromNj)\ **Post date:** [January 12, 2022, 12:03pm UTC](https://forum.inductiveautomation.com/t/block-transaction-db-to-opc-no-write-if-db-table-plc-size-are-not-the-same/33685/2 "2022-01-12T12:03:30Z")
I want to BUMP this issue. I recently did an Ignition upgrade from v7.7.0 to v7.9.18. The project that I updated had several transaction groups that stopped working after the upgrade. Ignition would log that the transaction group worked fine but no OPC tags would be written. I found this post and reset the block size to be less than the number of DB entries, which resulted in a successful transaction where the DB tags were written to the PLC. If the block size was greater than the # of DB entries, the transaction would not write any tag values. I contacted Ignition and after a lot of testing they confirmed that there is an issue the dates from 7.9.0 to 8.1.13 that will cause transaction groups to fail. I am not sure how it has taken so long for this to be discovered but hopefully it gets fixed in the next 7.9 and 8.1 release. ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [January 12, 2022, 2:04pm UTC](https://forum.inductiveautomation.com/t/block-transaction-db-to-opc-no-write-if-db-table-plc-size-are-not-the-same/33685/3 "2022-01-12T14:04:40Z")
Hmmm. I don’t see this in the changelogs. I thought it was fixed recently. (Doesn’t mean it will be fixed for 7.9, though. That is very close to EOL.) ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [January 12, 2022, 2:12pm UTC](https://forum.inductiveautomation.com/t/block-transaction-db-to-opc-no-write-if-db-table-plc-size-are-not-the-same/33685/4 "2022-01-12T14:12:37Z")
Closest thing I can find is described in the commit as “Option to write empty values for missing rows in block groups.”. It went into 8.0.11. ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/b/1/b12cc3657d73e9832667cd3087b72fe362ce9a26.png)