CREATE_CONVERSION(7pg16)

💅 CREATE CONVERSION — the 7pg16 manual page 💅

okay so bestie, this is CREATE CONVERSION, straight out of the 7pg16 manual, and yes it’s giving PostgreSQL 16.15 Documentation realness. We’re defining encoding conversions today. Main character energy only. ✨

🌸 NAME 🌸

CREATE_CONVERSION — define a new encoding conversion. Literally that. Slay.

✨ SYNOPSIS ✨

CREATE [ DEFAULT ] CONVERSION name
    FOR source_encoding TO dest_encoding FROM function_name

🦋 DESCRIPTION 🦋

okay so CREATE CONVERSION defines a new conversion between two character set encodings. no cap.

Conversions marked DEFAULT can be used for automatic encoding conversion between client and server. To support that usage, two conversions must be defined: one from encoding A to B, and one from encoding B to A. Both. Symmetry is the vibe.

To be able to create a conversion, you must have EXECUTE privilege on the function and CREATE privilege on the destination schema. Permission check, bestie. 💅

🎀 PARAMETERS 🎀

• DEFAULT — the DEFAULT clause indicates that this conversion is the default for this particular source to destination encoding. There should be only one default encoding in a schema for the encoding pair.
• name — the name of the conversion. The conversion name can be schema-qualified. If it is not, the conversion is defined in the current schema. The conversion name must be unique within a schema.
• source_encoding — the source encoding name.
• dest_encoding — the destination encoding name.
• function_name — the function used to perform the conversion. The function name can be schema-qualified. If it is not, the function will be looked up in the path.

The function must have the following signature:

conv_proc(
    integer,  -- source encoding ID
    integer,  -- destination encoding ID
    cstring,  -- source string (null terminated C string)
    internal, -- destination (fill with a null terminated C string)
    integer,  -- source string length
    boolean   -- if true, don't throw an error if conversion fails
) RETURNS integer;

The return value is the number of source bytes that were successfully converted. If the last argument is false, the function must throw an error on invalid input, and the return value is always equal to the source string length.

🌈 NOTES 🌈

⚠️ Neither the source nor the destination encoding can be SQL_ASCII, as the server's behavior for cases involving the SQL_ASCII “encoding” is hard-wired.

Use DROP CONVERSION to remove user-defined conversions.

The privileges required to create a conversion might be changed in a future release.

💖 EXAMPLES 💖

To create a conversion from encoding UTF8 to LATIN1 using myfunc:

CREATE CONVERSION myconv FOR 'UTF8' TO 'LATIN1' FROM myfunc;

🔥 COMPATIBILITY 🔥

CREATE CONVERSION is a PostgreSQL extension. There is no CREATE CONVERSION statement in the SQL standard, but a CREATE TRANSLATION statement that is very similar in purpose and syntax.

👑 SEE ALSO 👑

• ALTER CONVERSION (ALTER_CONVERSION(7))
• CREATE FUNCTION (CREATE_FUNCTION(7))
• DROP CONVERSION (DROP_CONVERSION(7))

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mwah 💖 — this was PostgreSQL 16.15, 2026, CREATE CONVERSION(7). bye bestie, go define some conversions responsibly 🫶