Reading analyze explain execution plan

[BrianR]

How do I know if  query A is faster than query B ? Here are the bottom summaries of two execution plans for two queries generating the same result. I believe B is better than A. 

Query A

/*

total: 1186

BAR.BAR_DATA read: 858 (72%)

BAR.BAR_PARENT read: 82 (6%)

DATA_FOO.DF_FK2_INDEX_E read: 26 (2%)

DATA_FOO.DATA_FOO_DATA read: 220 (18%)

*/

Query B

/*

total: 15

BAR.BAR_DATA read: 5 (33%)

DATA_FOO.DF_FK2_INDEX_E read: 1 (6%)

DATA_FOO.DATA_FOO_DATA read: 4 (26%)

DATA_FOO.DATA_FOO_UUID read: 5 (33%)

*/

What does the "total" number represent? Can I use the "total" as a reference point to the cost of the query? I know I can look at the scan counts and how indices are used in the rest of the plan to optimize. But, can I use the total as the overall cost?

[Thomas Mueller]

Hi,

This is the number of pages read from the file. Pages that are cached are not read from the file.

Regards,

Thomas

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