1. Introduction: What is "PostgreSQL ANSI ODBC"? At its core, the phrase "PostgreSQL ANSI ODBC" refers to a specific driver configuration within the psqlODBC driver suite—the official ODBC driver for PostgreSQL. This driver allows applications to connect to a PostgreSQL database using the Open Database Connectivity (ODBC) API, while adhering strictly to the ANSI SQL standard for character data types.
PostgreSQL Unicode(x64) PostgreSQL ANSI(x64) | Parameter | Recommended Value | Why | |-----------|------------------|-----| | Client Encoding | Leave blank or set to your ANSI code page name (e.g., WIN1252 , WIN1251 , SJIS ) | Overrides automatic detection. If wrong, data corruption occurs. | | Server Encoding | UTF8 | PostgreSQL default. The driver expects UTF-8 on the wire. | | Use Declare/Fetch | 1 (enabled) | Important for large result sets – forces server-side cursors. | | Bytea as LongVarBinary | 1 | Prevents accidental ANSI conversion of binary data. | | True is -1 | As needed for legacy VB (False=0, True=-1) | Affects boolean conversion. | Example Connection String (ANSI mode) DRIVER=PostgreSQL ANSI(x64); SERVER=192.168.1.100; PORT=5432; DATABASE=legacy_db; UID=appuser; PWD=secret; ClientEncoding=WIN1252; UseDeclareFetch=1; 5. Common Pitfalls and Troubleshooting Pitfall 1: Data Truncation or Garbled Text Symptom : Étienne becomes ?tienne or Étienne . Cause : Mismatch between application's ANSI code page and the ClientEncoding DSN setting. Fix : Determine the application's code page (e.g., by checking system locale). On Windows, run chcp in the app's environment. Set ClientEncoding accordingly. Pitfall 2: SQLDriverConnect Returns IM014 (Invalid connection string attribute) Cause : Using SQL_DRIVER_NOPROMPT with an ANSI driver but passing Unicode connection string buffers. Fix : Ensure all strings passed to SQLDriverConnect are SQLCHAR* , not SQLWCHAR* . Pitfall 3: ERROR: invalid byte sequence for encoding "UTF8": 0x80 Cause : Application sent a raw binary byte (e.g., 0x80) that is invalid in UTF-8. The ANSI-to-UTF8 conversion failed. Fix : Check that the application is not embedding binary data in text fields. Use BYTEA for binary. Pitfall 4: Double Byte Character Corruption (e.g., Chinese, Japanese) Symptom : Inserting "漢字" results in "姉帤" or random characters. Cause : The ANSI driver treats each byte independently. Shift-JIS or GB18030 multi-byte sequences are broken. Fix : Do not use ANSI driver for CJK. Switch to Unicode ODBC driver immediately. 6. Performance Considerations | Aspect | ANSI Driver | Unicode Driver | |--------|-------------|----------------| | Per-row conversion overhead | Yes – every column string is converted twice (app→UTF-8, UTF-8→app) | Minimal – UTF-8 to UTF-16 or direct binary copy | | Parameter binding | Slower with mixed data (ANSI→UTF-8 conversion on each bind) | Faster – native wide char | | Sorting/Comparison | Done on server (UTF-8) – no client impact | Same | | LOB handling | Same as Unicode (bytea/text streaming) | Same | postgresql ansi odbc
PostgreSQL ANSI(x64) Or, if both drivers are installed: This driver allows applications to connect to a