Hi all, 

I propose the patch that adds a function GetOldestXminExtended that is like 
GetOldestXmin but can ignore arbitrary vacuum flags. And then, rewrite 
GetOldestXmin to use it. Note that this is done so as not to change the 
behavior of GetOldestXmin.

This change will be useful for features that only reads rows that are visible 
by all transactions and could not wait specific processes (VACUUM, ANALYZE, 
etc...) for performance. Our company (Fujitsu) is developing such an extension. 
In our benchmark, we found that waiting an ANALYZE process created by 
autovacuum daemon often has a significant impact to the performance although 
the waited process do only reading as to the table. So I hope to ignore it 
using GetOldestXminExtend as below. The second argument represents flags to 


Note: We can ignore VACUUM processes or VACUUM with ANALYZE processes using the 
second option of GetOldesXmin, "ignoreVacuum". However, we cannot ignore only 
ANALYZE processes because the "ignoreVacuum" = true is same to the following.


This change should have no impact to the existing GetOldestXmin without slight 
overhead to call the function.

I'm not sure that this feature is useful in general.
Please let me know your opinion if you are interested.

Eiji Seki

Attachment: get_oldest_xmin_extended.patch
Description: get_oldest_xmin_extended.patch

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