PL/php vs PL/Perl feature comparison

This compares PL/php against PostgreSQL’s built-in PL/Perl and records which PL/Perl features PL/php now provides. Items marked added were implemented so that PL/php reaches parity with PL/Perl’s function set; a few items are intentionally out of scope, with the rationale given.

Language capabilities

Capability PL/Perl PL/php Notes
Scalar functions ✅ ✅
Array arguments / return (multi-dim) ✅ ✅
Composite / record arguments and return ✅ ✅
Set-returning functions (return_next) ✅ ✅
RETURNS TABLE / OUT / INOUT arguments ✅ ✅ PL/php also supports named parameters, which PL/Perl does not
Trigger functions ($_TD) ✅ ✅
Session-shared data %_SHARED $_SHARED
Private per-function data ❌ $_SD added like PL/Python’s SD; PL/Perl has no per-function store
Anonymous code blocks (DO) ✅ ✅ added DO $$ ... $$ LANGUAGE plphp
Procedures with transaction control ✅ ✅ added CALL a PROCEDURE; spi_commit/spi_rollback in a non-atomic context
Trusted (sandboxed) variant plperl (Safe.pm) ❌ by design PHP’s safe_mode was removed in 5.4; PL/php is untrusted/superuser-only (see Security)

Built-in functions

PL/Perl PL/php Notes
spi_exec_query spi_exec Runs a query, returns a result to iterate
spi_fetchrow / row access spi_fetch_row Iterates a materialized spi_exec result
(row count / status) spi_processed, spi_status, spi_rewind
spi_query spi_query added Opens a cursor; streams rows without materializing
spi_fetchrow spi_fetchrow added Fetch next row from a cursor; auto-closes at exhaustion
spi_cursor_close spi_cursor_close added Abandon a cursor early
errors trappable with eval try/catch (PgError $e) added PgError carries SQLSTATE, detail, and hint (richer than $@)
SRF returns array reference return an array from the SRF added One element per row, as an alternative to return_next
(no equivalent) spi_each(query, callable) added Streaming per-row callback; PL/Perl has no equivalent
elog(level, msg) elog added DEBUG/LOG/INFO/NOTICE/WARNING/ERROR; pg_raise remains as the older spelling
spi_prepare spi_prepare added Type names given as SQL type strings
spi_exec_prepared spi_exec_prepared added
spi_query_prepared spi_query_prepared added Opens a cursor for a prepared plan (was an alias of spi_exec_prepared in 2.0)
spi_freeplan spi_freeplan added
quote_literal quote_literal added
quote_nullable quote_nullable added
quote_ident quote_ident added
spi_commit / spi_rollback spi_commit / spi_rollback added Transaction control in a procedure invoked by CALL (non-atomic)
looks_like_number (none) Use PHP’s built-in is_numeric()
encode_bytea / decode_bytea (none) Use PHP’s bin2hex / hex2bin, base64_encode, etc.
encode_array_literal / encode_typed_literal (none) Marginal; build literals with the quoting helpers

Interpreter configuration

PL/Perl PL/php Notes
plperl.on_init plphp.on_init added PHP source run at interpreter initialization
(start proc, PL/Tcl-style) plphp.start_proc Runs a named PL/php function once per session
plperl.use_strict (none) No PHP equivalent; PHP is always “strict” about undefined functions

Transforms

PL/Perl PL/php Notes
jsonb_plperl jsonb_plphp added TRANSFORM FOR TYPE jsonb: native values in both directions
bool_plperl (none) PL/php already maps t/f; a transform would add little

Intentionally not implemented

  • Trusted/sandboxed language. PL/Perl’s plperl uses Safe.pm to restrict operations. Modern PHP has no equivalent (safe_mode was removed in PHP 5.4), so PL/php is untrusted only.

See doc/plphp.md for full usage of the functions listed above.