pg_eviltransform (Rust/pgrx)

中文文档 (Chinese README)

pg_eviltransform extends PostGIS ST_Transform with BD09/GCJ02 support.

It exposes one public function name, following the same overload interface as ST_Transform:

• ST_EvilTransform(geometry, to_srid integer)
• ST_EvilTransform(geometry, to_proj text)
• ST_EvilTransform(geometry, from_proj text, to_srid integer)
• ST_EvilTransform(geometry, from_proj text, to_proj text)

Behavior:

• If neither side uses custom coordinates, it delegates directly to ST_Transform.
• If BD09/GCJ02 is involved, it transforms via WGS84 (4326) when needed.

Custom SRIDs:

• 990001: GCJ02
• 990002: BD09

Regex SQL Variant

regex_eviltransform.sql defines Regex_EvilTransform(...) with the same overload interface as ST_EvilTransform(...).

Regex_EvilTransform is a SQL/PLpgSQL + regex implementation used for comparison and benchmarking against pg_eviltransform.

Citation

Patent reference for the regex-based SQL approach:

• CN112000902B

If you use the regex-based SQL approach, cite:

@patent{CN112000902B,
  title     = {用于地图区域绘制的方法、电子设备和存储介质},
  author    = {梁展钊},
  number    = {CN112000902B},
  year      = {2021},
  type      = {Chinese Patent},
  assignee  = {Shanghai Maice Data Technology Co., Ltd.; Maice (Shanghai) Intelligent Technology Co., Ltd.},
  url       = {https://patents.google.com/patent/CN112000902B}
}

Thanks

• googollee/eviltransform for the open-source coordinate transform implementation and reference formulas.

Requirements

• Rust stable 1.96+
• cargo-pgrx 0.19.1: cargo install --locked cargo-pgrx --version 0.19.1
• PostgreSQL + PostGIS (PG 14-19 packages; PG19 beta is experimental until PostgreSQL 19 GA)
• librttopo-dev (for the native GSERIALIZED fast path)

Packaging note:

• DEB packages have no hard runtime package dependency to keep installation lightweight.
• PostgreSQL/PostGIS are kept as suggested packages to avoid pulling a large dependency tree during apt install.
• Runtime still requires PostGIS (CREATE EXTENSION postgis) before CREATE EXTENSION pg_eviltransform.

Build

cargo pgrx init \
  --pg14=/usr/lib/postgresql/14/bin/pg_config \
  --pg15=/usr/lib/postgresql/15/bin/pg_config \
  --pg16=/usr/lib/postgresql/16/bin/pg_config \
  --pg17=/usr/lib/postgresql/17/bin/pg_config \
  --pg18=/usr/lib/postgresql/18/bin/pg_config \
  --pg19=/usr/lib/postgresql/19/bin/pg_config

cargo pgrx package --release --features pg18 --no-default-features --pg-config /usr/lib/postgresql/18/bin/pg_config
# Experimental PG19 beta:
cargo pgrx package --release --features pg19 --no-default-features --pg-config /usr/lib/postgresql/19/bin/pg_config

Test (native Rust)

cargo test
cargo pgrx test pg18 --features "pg18 pg_test"
# Experimental PG19 beta:
cargo pgrx test pg19 --features "pg19 pg_test"

Usage

-- Preferred: explicit literals (no need to remember custom SRID numbers)
SELECT ST_EvilTransform(ST_SetSRID('POINT(120 30)'::geometry, 4326), 'GCJ02');
SELECT ST_EvilTransform(ST_SetSRID('POINT(120 30)'::geometry, 4326), 'BD09');

-- Equivalent numeric custom SRID form
SELECT ST_EvilTransform(ST_SetSRID('POINT(120 30)'::geometry, 4326), 990001);

-- BD09 (990002) -> Web Mercator (3857)
SELECT ST_EvilTransform(ST_SetSRID('POINT(120.011070620552 30.0038830555128)'::geometry, 990002), 3857);

-- from_proj / to_proj overload with literals
SELECT ST_EvilTransform('POINT(120 30)'::geometry, 'EPSG:4326', 'GCJ02');

Jenks Natural Breaks

ST_JenksBins computes exact Jenks natural breaks and returns double precision[] bin edges.

Supported array inputs:

• numeric[]
• double precision[]
• real[]
• bigint[]
• integer[]
• smallint[]

Supported aggregate inputs:

• numeric
• double precision

Integer and real aggregate inputs can be cast to double precision or numeric. numeric inputs are accepted, but computation is normalized to finite f64, so output edges are floating-point values.

Examples:

-- Array form. NULL elements are ignored.
SELECT ST_JenksBins(ARRAY[1, 2, NULL, 10, 11]::numeric[], 2);

-- Streaming aggregate form. Prefer this for large tables.
SELECT ST_JenksBins(value, 7)
FROM big_table;

-- Lower bin edges instead of the default upper edges.
SELECT ST_JenksBins(value, 7, true)
FROM big_table;

Behavior:

• NULL inputs are ignored.
• breaks < 1, NaN, infinity, and numeric values outside finite f64 conversion range error.
• No valid input rows return NULL.
• If the distinct value count is less than or equal to breaks, sorted unique values are returned.

Benchmark (PG18)

Use the benchmark script to compare ST_EvilTransform and Regex_EvilTransform:

# optional env: PGHOST, PGPORT, PGUSER, PGDATABASE, ROWS
scripts/benchmark_pg18.sh
# Experimental PG19 beta:
PG_MAJOR=19 scripts/benchmark_pg18.sh

It will:

• Ensure postgis and pg_eviltransform extensions exist.
• Load regex_eviltransform.sql (creating Regex_EvilTransform).
• Generate benchmark data in public.bench_points.
• Run EXPLAIN (ANALYZE, BUFFERS) for ST_EvilTransform and Regex_EvilTransform.
• Write report to benchmark_pg18_report.txt (or custom output path).

Example:

ROWS=500000 PGDATABASE=testdb scripts/benchmark_pg18.sh /tmp/bench_pg18.txt

Latest run (PG18, ROWS=200000, report: benchmark_pg18_report.txt):

Scenario	ST_EvilTransform	Regex_EvilTransform	Speedup (Regex / ST)
4326 -> 990001	92.402 ms	2832.821 ms	30.7x
990002 -> 3857 (via 4326)	183.856 ms	8393.272 ms	45.7x

Experimental PG19 beta run (postgres:19beta1-trixie, ROWS=200000, report: benchmark_pg19_report.txt):

Scenario	ST_EvilTransform	Regex_EvilTransform	Speedup (Regex / ST)
4326 -> 990001	100.307 ms	2874.719 ms	28.7x
990002 -> 3857 (via 4326)	182.430 ms	8230.002 ms	45.1x

Jenks Benchmark

Use scripts/benchmark_jenksbins.sh to compare CartoDB's SQL baseline with Rust array and streaming aggregate forms:

# optional env: ROWS, DISTINCT_VALUES, BREAKS, WORK_MEM, PGHOST, PGPORT, PGUSER, PGDATABASE
scripts/benchmark_jenksbins.sh

The CartoDB baseline SQL used by the benchmark is vendored at scripts/CDB_JenksBins.sql with upstream attribution and license notes.

PG19 beta Docker run (ROWS=100000, DISTINCT_VALUES=1000, BREAKS=7, WORK_MEM=8MB):

Scenario	Execution time
CDB_JenksBins(array_agg(value::numeric), breaks)	95.785 ms
ST_JenksBins(array_agg(value), breaks)	11.381 ms
ST_JenksBins(value, breaks) streaming aggregate	8.210 ms

The streaming aggregate avoids materializing an array_agg input and keeps an internal distinct-value count map during aggregation.

Release Debian (Trixie, PG14-19)

scripts/release_debian_trixie.sh

This builds .deb artifacts under dist/:

• postgresql-14-pg-eviltransform_<version>_trixie_<arch>.deb
• postgresql-15-pg-eviltransform_<version>_trixie_<arch>.deb
• postgresql-16-pg-eviltransform_<version>_trixie_<arch>.deb
• postgresql-17-pg-eviltransform_<version>_trixie_<arch>.deb
• postgresql-18-pg-eviltransform_<version>_trixie_<arch>.deb
• postgresql-19-pg-eviltransform_<version>_trixie_<arch>.deb

GitHub Release CI publishes both amd64 and arm64 package artifacts (.deb + .rpm).

License

MIT. See LICENSE.