But then the object would need to be recreated, and that is said to not be needed. One reason I've heard for why this would help would be that the translation from character to byte takes some time. It has not indicated how bad the performance is or what kind of performance problem it is that has been experienced. The postings they have found have reported solving performance issues. Thank you for validating my feeling that this theory is not obvious. We are supposed to try the migration in TEST later this week with an implementation in PROD sometime next month. Are there any gotcha's that we need to be aware of. I'm trying to decide if we should just change the default to be CHAR. In the past, we've just ignored the '?' in the data, but I'm wondering if it really is some UNICODE character that we currently don't support. It's in a VARCHAR2(30) field, for example, and the underlying definition of the datatype is, of course, the default of bytes.
#Synalyze it set length to byte upgrade#
We're currently trying to upgrade from 9.2 to 10(.2 I think) and the DBA has run into a problem in our DEVL environment with some non-ascii data that was sent to us by an offsite system.
The following is stated for both the CHAR and VARCHAR2 datatypes:įor performance reasons, Oracle recommends that you use the NLS_LENGTH_SEMANTICS parameter to set length semantics and that you use the BYTE and CHAR qualifiers only when necessary to override the parameter. I use it so frequently that I've committed the URL to memory :) In passing, let me share an outstanding reference on charsets: So basically - a very modest "overhead" since the frequency of accented chars are around 2-3% in a string on average.įor latin-derived languages such as French, Spanish, German, it's almost the same - just increase the frequency of "funny-looking" (to an English native speaker ) chars (such as the accented chars), probably to 10%. It's worth noting that the Euro Symbol needs 3 bytes.įor Italian almost all chars need 1 byte, except the "accented chars" (à,è,ò, etcetera) that take 2 bytes, and the Euro Symbol that takes 3 bytes. But if you use the "new and suggested by Oracle" A元2UTF8 charset, it is "4", thanks to supplementary characters (click on "table B-2" on the link to get a nice breakdown by character type).
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