🐛 fix: fix embeddings multi-insert when there is issues with async task (#3530)

Author: arvinxx

src/database/server/migrations/0007_fix_embedding_table.sql

@@ -0,0 +1,18 @@
+-- step 1: create a temporary table to store the rows we want to keep
+CREATE TEMP TABLE embeddings_temp AS
+SELECT DISTINCT ON (chunk_id) *
+FROM embeddings
+ORDER BY chunk_id, random();
+
+-- step 2: delete all rows from the original table
+DELETE FROM embeddings;
+
+-- step 3: insert the rows we want to keep back into the original table
+INSERT INTO embeddings
+SELECT * FROM embeddings_temp;
+
+-- step 4: drop the temporary table
+DROP TABLE embeddings_temp;
+
+-- step 5: now it's safe to add the unique constraint
+ALTER TABLE "embeddings" ADD CONSTRAINT "embeddings_chunk_id_unique" UNIQUE("chunk_id");