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@ -10,7 +10,7 @@ |
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alink="#0000ff"> |
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<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1> |
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<P>Last updated: Sat Jun 3 20:17:01 EDT 2006</P> |
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<P>Last updated: Wed Jun 7 17:22:48 EDT 2006</P> |
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<P>Current maintainer: Bruce Momjian (<A href= |
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"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>) |
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@ -694,7 +694,7 @@ table?</TD><TD>unlimited</TD></TR> |
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<P>One limitation is that indexes can not be created on columns |
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longer than about 2,000 characters. Fortunately, such indexes are |
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rarely needed. Uniqueness is best guaranteed by a funtion index |
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rarely needed. Uniqueness is best guaranteed by a function index |
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of an MD5 hash of the long column, and full text indexing |
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allows for searching of words within the column.</P> |
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@ -812,8 +812,8 @@ table?</TD><TD>unlimited</TD></TR> |
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FROM tab |
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WHERE lower(col) = 'abc'; |
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</PRE> |
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This will not use an standard index. However, if you create a |
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expresssion index, it will be used: |
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This will not use an standard index. However, if you create an |
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expression index, it will be used: |
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<PRE> |
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CREATE INDEX tabindex ON tab (lower(col)); |
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</PRE> |
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@ -957,7 +957,7 @@ length</TD></TR> |
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<P>Every row that is created in PostgreSQL gets a unique |
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<SMALL>OID</SMALL> unless created <SMALL>WITHOUT OIDS</SMALL>. |
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O<SMALL>ID</SMALL>s are autotomatically assigned unique 4-byte |
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O<SMALL>ID</SMALL>s are automatically assigned unique 4-byte |
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integers that are unique across the entire installation. However, |
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they overflow at 4 billion, and then the O<SMALL>ID</SMALL>s start |
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being duplicated. PostgreSQL uses <SMALL>OID</SMALL>s to link its |
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