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August 2008

Why does even a small difference in SQL text cause a hard parse?

I just replied to an Oracle Forum Thread about why does even a small difference in SQL statement text cause it to be hard parsed and loaded as a different cursor. The reason is actually very simple – and I’m posting it into my blog too:

 The reason why a statement with even a minor difference in text is parsed as a separate cursor is due how Oracle looks up statements from library cache.

Why does even a small difference in SQL text cause a hard parse?

I just replied to an Oracle Forum Thread about why does even a small difference in SQL statement text cause it to be hard parsed and loaded as a different cursor. The reason is actually very simple – and I’m posting it into my blog too:

 The reason why a statement with even a minor difference in text is parsed as a separate cursor is due how Oracle looks up statements from library cache.

Why does even a small difference in SQL text cause a hard parse?

I just replied to an Oracle Forum Thread about why does even a small difference in SQL statement text cause it to be hard parsed and loaded as a different cursor. The reason is actually very simple – and I’m posting it into my blog too:

 The reason why a statement with even a minor difference in text is parsed as a separate cursor is due how Oracle looks up statements from library cache.

Why does even a small difference in SQL text cause a hard parse?

I just replied to an Oracle Forum Thread about why does even a small difference in SQL statement text cause it to be hard parsed and loaded as a different cursor. The reason is actually very simple – and I’m posting it into my blog too:

 The reason why a statement with even a minor difference in text is parsed as a separate cursor is due how Oracle looks up statements from library cache.

Script: Display valid values for multioption parameters (including hidden parameters)

I wrote a little script pvalid.sql for listing valid values for multioption parameters (the ones which are not string, number or boolean type, but accept a parameter from predetermined list, like optimizer_mode which can have values of ALL_ROWS, FIRST_ROWS, CHOOSE, FIRST_ROWS_1, etc).

The script accepts a (part of) Oracle parameter name as first argument, for example the following output is from Oracle 10.2.0.3 database:

Script: Display valid values for multioption parameters (including hidden parameters)

I wrote a little script pvalid.sql for listing valid values for multioption parameters (the ones which are not string, number or boolean type, but accept a parameter from predetermined list, like optimizer_mode which can have values of ALL_ROWS, FIRST_ROWS, CHOOSE, FIRST_ROWS_1, etc).

The script accepts a (part of) Oracle parameter name as first argument, for example the following output is from Oracle 10.2.0.3 database:

Script: Display valid values for multioption parameters (including hidden parameters)

I wrote a little script pvalid.sql for listing valid values for multioption parameters (the ones which are not string, number or boolean type, but accept a parameter from predetermined list, like optimizer_mode which can have values of ALL_ROWS, FIRST_ROWS, CHOOSE, FIRST_ROWS_1, etc).

The script accepts a (part of) Oracle parameter name as first argument, for example the following output is from Oracle 10.2.0.3 database:

Script: Display valid values for multioption parameters (including hidden parameters)

I wrote a little script pvalid.sql for listing valid values for multioption parameters (the ones which are not string, number or boolean type, but accept a parameter from predetermined list, like optimizer_mode which can have values of ALL_ROWS, FIRST_ROWS, CHOOSE, FIRST_ROWS_1, etc).

The script accepts a (part of) Oracle parameter name as first argument, for example the following output is from Oracle 10.2.0.3 database:

Effective Testing

I’ve been following a number of threads on forums.oracle.com recently – the quality of discussion seems to have improved markedly there since I gave up on it in 2001. Anyway there was a thread about interpreting the AWR report that Oracle provides (at extra cost) and which is very smilar to the Statspack report. The [...]

The simplest query for checking what’s happening in a database

Update: If you are able to download & run scripts, it’s probably better to use my Snapper and @ashtop.sql tools for performance analysis. Neither of these scripts require any installation, Ashtop requires Diagnostics Pack (as it uses ASH), Snapper doesn’t even need that - it can also run on Standard Edition! Search for them in my blog, or check an intro video in my YouTube channel.
When someone asks you to take a quick look into database performance and for whatever reason you can’t run your usual scripts or performance tools on there, ), then what query would you run first?