G
George Potemkin
Guest
Some numbers for the tests with sports2000 db: FOR EACH OrderLine NO-LOCK NO-PREFETCH /* SHARE-LOCK */: ACCUMULATE "rec":U (COUNT). END. promon/Activity: Servers NO-LOCK NO-PREFETCH SHARE-LOCK Incr Messages received 13979 27949 +13970 Messages sent 13976 13976 Bytes received 1509396 2124076 +614680 Bytes sent 2086135 2086135 Records received 0 0 Records sent 13970 13970 Queries received 13971 13971 The sizes of individual network messages: Queries received: 108 bytes Release Lock: 44 bytes Records sent: 149 bytes Bytes sent: 2,086,135 bytes Record size: 605,019 bytes (according to tabanalys) SHARE-LOCK query is drastically slower on CentOS 7 because it uses the additional 13970 messages to release a lock. But the main difference, me think, is very small size of these messages. I would run the similar tests against a table where I can control the size of the records. The aim is to check how the execution time of NO-LOCK NO-PREFETCH depends from record's sizes (from the network message sizes). It looks like the smaller network messages the slower the query.
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