chore: gather more stat4 samples

deps/defines.gypi

@@ -35,6 +35,7 @@
     'SQLITE_OMIT_SHARED_CACHE',
     'SQLITE_OMIT_TCL_VARIABLE',
     'SQLITE_SOUNDEX',
+    'SQLITE_STAT4_SAMPLES=128',
     'SQLITE_THREADSAFE=2',
     'SQLITE_TRACE_SIZE_LIMIT=32',
     'SQLITE_USE_URI=1',

deps/download.sh

@@ -55,6 +55,7 @@ SQLITE_OMIT_PROGRESS_CALLBACK
 SQLITE_OMIT_SHARED_CACHE
 SQLITE_OMIT_TCL_VARIABLE
 SQLITE_SOUNDEX
+SQLITE_STAT4_SAMPLES=128
 SQLITE_THREADSAFE=2
 SQLITE_TRACE_SIZE_LIMIT=32
 SQLITE_USE_URI=1

docs/compilation.md

@@ -80,6 +80,7 @@ SQLITE_OMIT_PROGRESS_CALLBACK
 SQLITE_OMIT_SHARED_CACHE
 SQLITE_OMIT_TCL_VARIABLE
 SQLITE_SOUNDEX
+SQLITE_STAT4_SAMPLES=128
 SQLITE_THREADSAFE=2
 SQLITE_TRACE_SIZE_LIMIT=32
 SQLITE_USE_URI=1

test/51.stat4-samples.js

@@ -0,0 +1,37 @@
+'use strict';
+const Database = require('../.');
+
+describe('SQLITE_STAT4_SAMPLES', function () {
+	beforeEach(function () {
+		this.db = new Database(util.next());
+	});
+	afterEach(function () {
+		this.db.close();
+	});
+
+	it('is compiled with STAT4_SAMPLES=128', function () {
+		const options = this.db.pragma('compile_options').map(r => r.compile_options);
+		expect(options).to.include('STAT4_SAMPLES=128');
+	});
+
+	it('ANALYZE collects more than the default 24 samples per index', function () {
+		this.db.prepare('CREATE TABLE t (x INTEGER)').run();
+		this.db.prepare('CREATE INDEX t_x ON t (x)').run();
+
+		const rowCount = 5000;
+		const insert = this.db.prepare('INSERT INTO t (x) VALUES (?)');
+		const insertMany = this.db.transaction(() => {
+			for (let i = 0; i < rowCount; i++) insert.run(i);
+		});
+		insertMany();
+
+		this.db.exec('ANALYZE');
+
+		const samples = this.db
+			.prepare("SELECT COUNT(*) AS n FROM sqlite_stat4 WHERE idx = 't_x'")
+			.get().n;
+
+		expect(samples).to.be.above(24);
+		expect(samples).to.be.at.most(128);
+	});
+});