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Consider two queries from attached zip. The only difference between them is:
Q1:
select
char_length(mon$explained_plan)
,(selectcount(*) from r4)
,(selectcount(*) from rn)
,(selectcount(*) from rn)
from mon$statements
Q2:
select
char_length(mon$explained_plan)
,(selectcount(*) from r4)
,(selectcount(*) from rn)
--,(select count(*) from rn)from mon$statements
(i.e. Q2 is simplified: one of columns is excluded from selection).
Q1 has length of mon$explained plan = 64436 and length of output in ISQL when "set explain on" = 64944 (difference ~500 can be explained by number of occurences ascii_char(13) in output of 'set explain on').
Q2 (which is simplified case of Q1) has length of mon$explained plan = 63237 but length of ouput in ISQL when "set explain on" = 33024. Plan in ISQL looks as:
===
-> Nested Loop Join (anti)
-> Recursion
-> First N Records
-> Window
-> Record Buffer (record length: ...
===
summary: ISQL output of explained plan is shorter by ~ 2 times when query is simplified by removing one of selected columns from it => ISQL plan output is unexpectedly truncated after a query is simplified to become shorter
Submitted by: @pavel-zotov
Attachments:
isql-explained-plan-cut-off-when-query-is-simlified.zip
Consider two queries from attached zip. The only difference between them is:
Q1:
Q2:
(i.e. Q2 is simplified: one of columns is excluded from selection).
Q1 has length of
mon$explained plan
= 64436 and length of output in ISQL when "set explain on
" = 64944 (difference ~500 can be explained by number of occurencesascii_char(13)
in output of 'set explain on').Q2 (which is simplified case of Q1) has length of
mon$explained plan
= 63237 but length of ouput in ISQL when "set explain on" = 33024. Plan in ISQL looks as:Checked on WI-V3.0.0.32256.
Commits: 24b7a79 FirebirdSQL/fbt-repository@f60a6b7
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