Tom Lane wrote:
If I understood what I was reading, this would take several things: * Remove the "special UTF-8 check" in pg_verifymbstr; * Extend pg_utf2wchar_with_len and pg_utf_mblen to handle the 4-byte case; * Set maxmblen to 4 in the pg_wchar_table entry for UTF-8.
Are there any other places that would have to change? Would this break anything? The testing aspect is what's bothering me at the moment.
Does this change what client_encoding = UNICODE might produce? The JDBC driver will need some tweaking to handle this -- Java uses UTF-16 internally and I think some supplementary character (?) scheme for values above 0xffff as of JDK 1.5.
Java doesn't handle UCS above 0xffff? I didn't know that. As long as you put in/out JDBC, it shouldn't be a problem. However if other APIs put in such a data, you will get into trouble...
Internally, Java strings are arrays of UTF-16 values. Before JDK 1.5, all the string-manipulation library routines assumed that one code point == one UTF-16 value, so you can't represent values above 0xffff. The 1.5 libraries understand using supplementary characters to use multiple UTF-16 values per code point. See http://java.sun.com/developer/technicalArticles/Intl/Supplementary/
However, the JDBC driver needs to be taught about how to translate between UTF-8 representations of code points above 0xffff and pairs of UTF-16 values. Previously it didn't need to do anything since the server didn't use those high values. It's a minor thing..
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