Does anyone know what this scheduled task is in IDS 14.10.FC2? It executes C UDR adm_pfsc_boost and the description is "PFSC Boost", so no clues there...

Also found a minor bug in InformixHQ that you can't specify zero in Automated Update Statistics / Configuration / AUS_PDQ which would cause noise in the message log for restricted editions. You can set it to zero using Task Scheduler / Auto Update Statistics Refresh / Parameters, though. Alternatively:

UPDATE ph_threshold SET value = 0 WHERE name = 'AUS_PDQ';

------------------------------
Regards,
Doug Lawry
------------------------------

#Informix

Hi Doug,
This feature is available since 14.10.xc2.

The output of the onstat -g cfg command shows that the feature is enabled by default.
The pfsc_boost task seems to be related to this.

I found a description of that feature (PFSC, Partition Free Space Cache) in JC Lengyel's IIUG2019 conference presentation.


And it could not modify the AUS_PDQ to 0 as shown below in InformixHQ v2. Thank you for sharing the information.







------------------------------
SangGyu Jeong
Software Engineer
Infrasoft
Seoul Korea, Republic of
------------------------------

Original Message:
Sent: Thu October 31, 2019 02:22 PM
From: Doug Lawry
Subject: pfsc_boost

Does anyone know what this scheduled task is in IDS 14.10.FC2? It executes C UDR adm_pfsc_boost and the description is "PFSC Boost", so no clues there...

Also found a minor bug in InformixHQ that you can't specify zero in Automated Update Statistics / Configuration / AUS_PDQ which would cause noise in the message log for restricted editions. You can set it to zero using Task Scheduler / Auto Update Statistics Refresh / Parameters, though. Alternatively:

UPDATE ph_threshold SET value = 0 WHERE name = 'AUS_PDQ';

------------------------------
Regards,
Doug Lawry
------------------------------
#Informix

Thanks, SangGyu. For those who haven't seen it, JC Lengyel's presentation says:



------------------------------
Doug Lawry
------------------------------

Original Message:
Sent: Fri November 01, 2019 01:43 AM
From: SangGyu Jeong
Subject: pfsc_boost

Hi Doug,
This feature is available since 14.10.xc2.

The output of the onstat -g cfg command shows that the feature is enabled by default.
The pfsc_boost task seems to be related to this.

I found a description of that feature (PFSC, Partition Free Space Cache) in JC Lengyel's IIUG2019 conference presentation.


And it could not modify the AUS_PDQ to 0 as shown below in InformixHQ v2. Thank you for sharing the information.

------------------------------
SangGyu Jeong
Software Engineer
Infrasoft
Seoul Korea, Republic of

Original Message:
Sent: Thu October 31, 2019 02:22 PM
From: Doug Lawry
Subject: pfsc_boost

Does anyone know what this scheduled task is in IDS 14.10.FC2? It executes C UDR adm_pfsc_boost and the description is "PFSC Boost", so no clues there...

Also found a minor bug in InformixHQ that you can't specify zero in Automated Update Statistics / Configuration / AUS_PDQ which would cause noise in the message log for restricted editions. You can set it to zero using Task Scheduler / Auto Update Statistics Refresh / Parameters, though. Alternatively:

UPDATE ph_threshold SET value = 0 WHERE name = 'AUS_PDQ';

------------------------------
Regards,
Doug Lawry
------------------------------
#Informix

Since MAX_FILL_DATA_PAGES was implemented there has been a problem with it for tables with variable length columns, high insert activity, and frequent deletes. Review: Before MAX_FILL_DATA_PAGES and when it is disabled, Informix will only place a new variable length row on a page if the maximum length of the row would fit. This could cause wasted storage up to 50% for some tables. When this feature is enabled Informix tries to place new variable length rows onto pages that have room for that particular row so long as 10% is free on the page afterwards for rows to expand into without having to be moved to a forwarding page. On a table with deletes that might mean checking many many pages before finding a home for the new row and tends to severely slow down systems that perform many many inserts to these tables. That is because the bitmap pages only tell the engine whether a page is full, nearly full, half full, or empty not how much space is left on it. So, in 14.10.FC2 they implemented a cache recording the free space on not-full pages for variable length tables so the engine just has to check the cache instead of having to read many many pages into memory to check their free space.

The task manager task that you are seeing, Doug, is how the cache gets populated. It is enabled by default. The feature to use the cache or not to is controlled by the new ONCONFIG parameter PFSC which is set to '1' - ON by default.

------------------------------
Art Kagel
------------------------------

Original Message:
Sent: Thu October 31, 2019 02:22 PM
From: Doug Lawry
Subject: pfsc_boost

Does anyone know what this scheduled task is in IDS 14.10.FC2? It executes C UDR adm_pfsc_boost and the description is "PFSC Boost", so no clues there...

Also found a minor bug in InformixHQ that you can't specify zero in Automated Update Statistics / Configuration / AUS_PDQ which would cause noise in the message log for restricted editions. You can set it to zero using Task Scheduler / Auto Update Statistics Refresh / Parameters, though. Alternatively:

UPDATE ph_threshold SET value = 0 WHERE name = 'AUS_PDQ';

------------------------------
Regards,
Doug Lawry
------------------------------
#Informix

Thanks, Art.

------------------------------
Doug Lawry
------------------------------

Original Message:
Sent: Fri November 01, 2019 06:07 AM
From: Art Kagel
Subject: pfsc_boost

Since MAX_FILL_DATA_PAGES was implemented there has been a problem with it for tables with variable length columns, high insert activity, and frequent deletes. Review: Before MAX_FILL_DATA_PAGES and when it is disabled, Informix will only place a new variable length row on a page if the maximum length of the row would fit. This could cause wasted storage up to 50% for some tables. When this feature is enabled Informix tries to place new variable length rows onto pages that have room for that particular row so long as 10% is free on the page afterwards for rows to expand into without having to be moved to a forwarding page. On a table with deletes that might mean checking many many pages before finding a home for the new row and tends to severely slow down systems that perform many many inserts to these tables. That is because the bitmap pages only tell the engine whether a page is full, nearly full, half full, or empty not how much space is left on it. So, in 14.10.FC2 they implemented a cache recording the free space on not-full pages for variable length tables so the engine just has to check the cache instead of having to read many many pages into memory to check their free space.

The task manager task that you are seeing, Doug, is how the cache gets populated. It is enabled by default. The feature to use the cache or not to is controlled by the new ONCONFIG parameter PFSC which is set to '1' - ON by default.

------------------------------
Art Kagel

Original Message:
Sent: Thu October 31, 2019 02:22 PM
From: Doug Lawry
Subject: pfsc_boost

Does anyone know what this scheduled task is in IDS 14.10.FC2? It executes C UDR adm_pfsc_boost and the description is "PFSC Boost", so no clues there...

Also found a minor bug in InformixHQ that you can't specify zero in Automated Update Statistics / Configuration / AUS_PDQ which would cause noise in the message log for restricted editions. You can set it to zero using Task Scheduler / Auto Update Statistics Refresh / Parameters, though. Alternatively:

UPDATE ph_threshold SET value = 0 WHERE name = 'AUS_PDQ';

------------------------------
Regards,
Doug Lawry
------------------------------
#Informix