Added pg.zig example

Author: ankane

.github/workflows/build.yml

@@ -17,4 +17,5 @@ jobs:
           make
           sudo make install
       - run: zig build
+      - run: zig-out/bin/pg
       - run: zig-out/bin/libpq

README.md

@@ -2,16 +2,56 @@
 
 [pgvector](https://github.com/pgvector/pgvector) examples for Zig
 
-Supports [libpq](https://www.postgresql.org/docs/current/libpq.html)
+Supports [pg.zig](https://github.com/karlseguin/pg.zig) and [libpq](https://www.postgresql.org/docs/current/libpq.html)
 
 [![Build Status](https://github.com/pgvector/pgvector-zig/actions/workflows/build.yml/badge.svg)](https://github.com/pgvector/pgvector-zig/actions)
 
 ## Getting Started
 
 Follow the instructions for your database library:
 
+- [pg.zig](#pg-zig)
 - [libpq](#libpq)
 
+## pg.zig
+
+Enable the extension
+
+```zig
+_ = try conn.exec("CREATE EXTENSION IF NOT EXISTS vector", .{});
+```
+
+Create a table
+
+```zig
+_ = try conn.exec("CREATE TABLE items (id bigserial PRIMARY KEY, embedding vector(3))", .{});
+```
+
+Insert vectors
+
+```zig
+const params = .{ "[1,1,1]", "[2,2,2]", "[1,1,2]" };
+_ = try conn.exec("INSERT INTO items (embedding) VALUES ($1), ($2), ($3)", params);
+```
+
+Get the nearest neighbors
+
+```zig
+var result = try conn.query("SELECT id FROM items ORDER BY embedding <-> $1 LIMIT 5", .{"[1,1,1]"});
+```
+
+Add an approximate index
+
+```zig
+_ = try conn.exec("CREATE INDEX ON items USING hnsw (embedding vector_l2_ops)", .{});
+// or
+_ = try conn.exec("CREATE INDEX ON items USING ivfflat (embedding vector_l2_ops) WITH (lists = 100)", .{});
+```
+
+Use `vector_ip_ops` for inner product and `vector_cosine_ops` for cosine distance
+
+See a [full example](examples/pg.zig)
+
 ## libpq
 
 Import libpq
@@ -76,6 +116,7 @@ git clone https://github.com/pgvector/pgvector-zig.git
 cd pgvector-zig
 createdb pgvector_zig_test
 zig build
+zig-out/bin/pg
 zig-out/bin/libpq
 ```
 

build.zig

@@ -1,6 +1,17 @@
 const std = @import("std");
 
 pub fn build(b: *std.Build) void {
+    const pgExe = b.addExecutable(.{
+        .name = "pg",
+        .root_source_file = b.path("examples/pg.zig"),
+        .target = b.graph.host,
+    });
+    pgExe.linkSystemLibrary("pq");
+    pgExe.linkLibC();
+    const pg = b.dependency("pg", .{});
+    pgExe.root_module.addImport("pg", pg.module("pg"));
+    b.installArtifact(pgExe);
+
     const libpqExe = b.addExecutable(.{
         .name = "libpq",
         .root_source_file = b.path("examples/libpq.zig"),

build.zig.zon

@@ -0,0 +1,18 @@
+.{
+    .name = .pgvector,
+    .version = "0.0.0",
+    .fingerprint = 0x2dcfd56a3910ab6c,
+    .minimum_zig_version = "0.14.0",
+    .dependencies = .{
+        .pg = .{
+            .url = "git+https://github.com/karlseguin/pg.zig?ref=master#740b6bfe31bc3ebc81b7bc97fe883871da2604c7",
+            .hash = "pg-0.0.0-Wp_7gQr-BQAMQ8q9R0TzXrVgsyLVubJpg7mg_CSSIYqI",
+        },
+    },
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "LICENSE.txt",
+        "README.md",
+    },
+}

examples/pg.zig

@@ -0,0 +1,31 @@
+const pg = @import("pg");
+const std = @import("std");
+const print = std.debug.print;
+
+pub fn main() !void {
+    const allocator = std.heap.c_allocator;
+    var pool = try pg.Pool.init(allocator, .{ .auth = .{
+        .username = std.mem.sliceTo(std.c.getenv("USER").?, 0),
+        .database = "pgvector_zig_test",
+    } });
+    defer pool.deinit();
+
+    const conn = try pool.acquire();
+    defer pool.release(conn);
+
+    _ = try conn.exec("CREATE EXTENSION IF NOT EXISTS vector", .{});
+
+    _ = try conn.exec("DROP TABLE IF EXISTS pg_items", .{});
+
+    _ = try conn.exec("CREATE TABLE pg_items (id bigserial PRIMARY KEY, embedding vector(3))", .{});
+
+    const params = .{ "[1,1,1]", "[2,2,2]", "[1,1,2]" };
+    _ = try conn.exec("INSERT INTO pg_items (embedding) VALUES ($1), ($2), ($3)", params);
+
+    var result = try conn.query("SELECT id FROM pg_items ORDER BY embedding <-> $1 LIMIT 5", .{"[1,1,1]"});
+    defer result.deinit();
+    while (try result.next()) |row| {
+        const id = row.get(i64, 0);
+        print("{d}\n", .{id});
+    }
+}