Hello,
While I'm reviewing patches for parallel operations, it occured to me that we may need to correct the words and enrich
contentin "15. Parallel Query". I don't have a concrete image of how the content should be yet, and I think the
documentationmay be improved after the feature freeze (i.e. April.) Is anyone already doing this kind of
modifications?
First, as parallel data updates are being introduced, the chapter title "Parallel Query" should be changed to "Parallel
Execution"or "Parallel Operation". It's confusing to see that Postgres uses "query" to also mean statements other than
SELECT,but the SQL standard seems to differentiate them; SELECT is explained in "7 Query expressions" and
INSERT/DELETE/UPDATEetc. are described in "14 Data manipulation". Following the SQL standard, Postgres manual have
separatechapters "6. Data Manipulation" and "7. Queries". (e.g. query plan in EXPLAIN should have been execution plan?
But it's too late now.) The chapter content should also be changed to use appropriate words carefully.
FYI, Oracle wisely give the chapter title "8 Using Parallel Execution" [1]. SQL Server isn't very clear, but it seems
thatit doesn't use "query" for INSERT, like in "The TABLOCK hint can enable parallel insert operations." [2] [3]
Second, I expected to see descriptions in "15. Parallel Query" that there are other (recently added) parallel
operationssuch as parallel index build and parallel VACUUM, but I didn't find them. Also, I couldn't find information
onparallelism in possible chapters such as "11. Indexes" or "25. Routine Database Maintenance Tasks". Where can users
noticethat they can parallelize and speed up those operations? Only in reference pages? I think it's better to have
thosedescriptions in the Parallel Query chapter.
If nobody hasn't started making this kind of modifications, can we deter it after the feature freeze? Or should people
involvedin developing parallel features cooperate to revise the manual as part of their patches?
Regards
Takayuki Tsunakawa
[1]
8 Using Parallel Execution
https://docs.oracle.com/en/database/oracle/oracle-database/21/vldbg/using-parallel.html#GUID-3E2AE088-2505-465E-A8B2-AC38813EA355
[2]
Query Processing Architecture Guide
https://docs.microsoft.com/en-us/sql/relational-databases/query-processing-architecture-guide?view=sql-server-ver15
[3]
INSERT (Transact-SQL)
https://docs.microsoft.com/en-us/sql/t-sql/statements/insert-transact-sql?view=sql-server-ver15#best-practices
Regards
Takayuki Tsunakawa
