11.11. Indexes and Collations

11.11. Indexes and Collations
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+ An index can support only one collation per index column. + If multiple collations are of interest, multiple indexes may be needed. +

+ Consider these statements: +

+CREATE TABLE test1c (
+    id integer,
+    content varchar COLLATE "x"
+);
+
+CREATE INDEX test1c_content_index ON test1c (content);
+

+ The index automatically uses the collation of the + underlying column. So a query of the form +

+SELECT * FROM test1c WHERE content > constant;
+

+ could use the index, because the comparison will by default use the + collation of the column. However, this index cannot accelerate queries + that involve some other collation. So if queries of the form, say, +

+SELECT * FROM test1c WHERE content > constant COLLATE "y";
+

+ are also of interest, an additional index could be created that supports + the "y" collation, like this: +

+CREATE INDEX test1c_content_y_index ON test1c (content COLLATE "y");
+

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