add backward compatibility test for on-disk format of vector index

Author: sivukhin

libsql-sqlite3/.gitignore

@@ -41,7 +41,10 @@ libsql.pc
 /sqlite3session.h
 tclsqlite.lo
 tclsqlite.o
-testdir/
+
+testdir/*
+!testdir/libsql_vector_index_v2.db
+
 tsrc/
 dbhash
 fuzzcheck

libsql-sqlite3/test/libsql_vector_index.test

@@ -531,3 +531,32 @@ do_execsql_test vector-index-attach-query {
   ATTACH DATABASE 'test2.db' AS t;
   SELECT * FROM vector_top_k('t.t_attach_idx', vector('[3,4,5]'), 4);
 } {3 4 2 1}
+
+# v2.db created with simple command (with LibSQL built from commit 4a5f373a298cc751d9ca56662eaaf879eefff279):
+#   ./sqlite3 v2.db --cmd "CREATE TABLE t (id TEXT, e FLOAT32(4)); CREATE INDEX t_idx ON t (libsql_vector_idx(e)); INSERT INTO t VALUES ('a', vector32('[1,2,3,4]')), ('b', vector32('[-100,-100,-100,-100]')), ('c', vector32('[10,10,-10,-10]')), ('d', vector32('[-1,2,3,4]'))"
+sqlite3 dbv2 libsql_vector_index_v2.db
+
+# select version and check that it equals to 2
+do_test vector-index-v2-read {
+  execsql { SELECT substr(hex(metadata), 0, 18) FROM libsql_vector_meta_shadow WHERE name = 't_idx'; } dbv2
+} {01020000000000000}
+
+do_test vector-index-v2-read {
+  execsql { SELECT vector_extract(e) FROM t; } dbv2
+} {{[1,2,3,4]} {[-100,-100,-100,-100]} {[10,10,-10,-10]} {[-1,2,3,4]}}
+
+do_test vector-index-v2-query-1 {
+  execsql { SELECT t.id FROM vector_top_k('t_idx', vector('[1,1,1,1]'), 3) i INNER JOIN t ON t.rowid = i.id; } dbv2
+} {a d c}
+
+do_test vector-index-v2-query-2 {
+  execsql { SELECT t.id FROM vector_top_k('t_idx', vector('[-1,-1,-1,-1]'), 3) i INNER JOIN t ON t.rowid = i.id; } dbv2
+} {b c d}
+
+do_test vector-index-v2-query-3 {
+  execsql { SELECT t.id FROM vector_top_k('t_idx', vector('[1,1,-1,-1]'), 3) i INNER JOIN t ON t.rowid = i.id; } dbv2
+} {c b a}
+
+do_test vector-index-v2-query-4 {
+  execsql { SELECT t.id FROM vector_top_k('t_idx', vector('[-1,1,1,1]'), 3) i INNER JOIN t ON t.rowid = i.id; } dbv2
+} {d a c}