diff --git a/blobs.go b/blobs.go
index 578773376..1fb310183 100644
--- a/blobs.go
+++ b/blobs.go
@@ -36,7 +36,7 @@ type blobsTable struct {
 // BlobsSchema is the schema for the blobs table.
 var BlobsSchema = sql.Schema{
 	{Name: "repository_id", Type: sql.Text, Nullable: false, Source: BlobsTableName},
-	{Name: "blob_hash", Type: sql.Text, Nullable: false, Source: BlobsTableName},
+	{Name: "blob_hash", Type: sql.VarChar(40), Nullable: false, Source: BlobsTableName},
 	{Name: "blob_size", Type: sql.Int64, Nullable: false, Source: BlobsTableName},
 	{Name: "blob_content", Type: sql.Blob, Nullable: false, Source: BlobsTableName},
 }
diff --git a/commit_blobs.go b/commit_blobs.go
index 83f4f71ce..41b241d23 100644
--- a/commit_blobs.go
+++ b/commit_blobs.go
@@ -19,8 +19,8 @@ type commitBlobsTable struct {
 // CommitBlobsSchema is the schema for the commit blobs table.
 var CommitBlobsSchema = sql.Schema{
 	{Name: "repository_id", Type: sql.Text, Source: CommitBlobsTableName},
-	{Name: "commit_hash", Type: sql.Text, Source: CommitBlobsTableName},
-	{Name: "blob_hash", Type: sql.Text, Source: CommitBlobsTableName},
+	{Name: "commit_hash", Type: sql.VarChar(40), Source: CommitBlobsTableName},
+	{Name: "blob_hash", Type: sql.VarChar(40), Source: CommitBlobsTableName},
 }
 
 var _ Table = (*commitBlobsTable)(nil)
diff --git a/commit_files.go b/commit_files.go
index 2f6518933..848b62508 100644
--- a/commit_files.go
+++ b/commit_files.go
@@ -24,10 +24,10 @@ type commitFilesTable struct {
 // CommitFilesSchema is the schema for the commit trees table.
 var CommitFilesSchema = sql.Schema{
 	{Name: "repository_id", Type: sql.Text, Source: CommitFilesTableName},
-	{Name: "commit_hash", Type: sql.Text, Source: CommitFilesTableName},
+	{Name: "commit_hash", Type: sql.VarChar(40), Source: CommitFilesTableName},
 	{Name: "file_path", Type: sql.Text, Source: CommitFilesTableName},
-	{Name: "blob_hash", Type: sql.Text, Source: CommitFilesTableName},
-	{Name: "tree_hash", Type: sql.Text, Source: CommitFilesTableName},
+	{Name: "blob_hash", Type: sql.VarChar(40), Source: CommitFilesTableName},
+	{Name: "tree_hash", Type: sql.VarChar(40), Source: CommitFilesTableName},
 }
 
 func newCommitFilesTable(pool *RepositoryPool) Indexable {
diff --git a/commit_trees.go b/commit_trees.go
index b1f1c8cd1..6d0c84c67 100644
--- a/commit_trees.go
+++ b/commit_trees.go
@@ -21,8 +21,8 @@ type commitTreesTable struct {
 // CommitTreesSchema is the schema for the commit trees table.
 var CommitTreesSchema = sql.Schema{
 	{Name: "repository_id", Type: sql.Text, Source: CommitTreesTableName},
-	{Name: "commit_hash", Type: sql.Text, Source: CommitTreesTableName},
-	{Name: "tree_hash", Type: sql.Text, Source: CommitTreesTableName},
+	{Name: "commit_hash", Type: sql.VarChar(40), Source: CommitTreesTableName},
+	{Name: "tree_hash", Type: sql.VarChar(40), Source: CommitTreesTableName},
 }
 
 func newCommitTreesTable(pool *RepositoryPool) Indexable {
diff --git a/commits.go b/commits.go
index b555c4ba4..c9fa6da49 100644
--- a/commits.go
+++ b/commits.go
@@ -20,16 +20,16 @@ type commitsTable struct {
 // CommitsSchema is the schema for the commits table.
 var CommitsSchema = sql.Schema{
 	{Name: "repository_id", Type: sql.Text, Nullable: false, Source: CommitsTableName},
-	{Name: "commit_hash", Type: sql.Text, Nullable: false, Source: CommitsTableName},
+	{Name: "commit_hash", Type: sql.VarChar(40), Nullable: false, Source: CommitsTableName},
 	{Name: "commit_author_name", Type: sql.Text, Nullable: false, Source: CommitsTableName},
-	{Name: "commit_author_email", Type: sql.Text, Nullable: false, Source: CommitsTableName},
+	{Name: "commit_author_email", Type: sql.VarChar(254), Nullable: false, Source: CommitsTableName},
 	{Name: "commit_author_when", Type: sql.Timestamp, Nullable: false, Source: CommitsTableName},
 	{Name: "committer_name", Type: sql.Text, Nullable: false, Source: CommitsTableName},
-	{Name: "committer_email", Type: sql.Text, Nullable: false, Source: CommitsTableName},
+	{Name: "committer_email", Type: sql.VarChar(254), Nullable: false, Source: CommitsTableName},
 	{Name: "committer_when", Type: sql.Timestamp, Nullable: false, Source: CommitsTableName},
 	{Name: "commit_message", Type: sql.Text, Nullable: false, Source: CommitsTableName},
-	{Name: "tree_hash", Type: sql.Text, Nullable: false, Source: CommitsTableName},
-	{Name: "commit_parents", Type: sql.Array(sql.Text), Nullable: false, Source: CommitsTableName},
+	{Name: "tree_hash", Type: sql.VarChar(40), Nullable: false, Source: CommitsTableName},
+	{Name: "commit_parents", Type: sql.Array(sql.VarChar(40)), Nullable: false, Source: CommitsTableName},
 }
 
 func newCommitsTable(pool *RepositoryPool) *commitsTable {
diff --git a/files.go b/files.go
index 14936acf1..a5b8fb9bb 100644
--- a/files.go
+++ b/files.go
@@ -23,9 +23,9 @@ type filesTable struct {
 var FilesSchema = sql.Schema{
 	{Name: "repository_id", Type: sql.Text, Source: "files"},
 	{Name: "file_path", Type: sql.Text, Source: "files"},
-	{Name: "blob_hash", Type: sql.Text, Source: "files"},
-	{Name: "tree_hash", Type: sql.Text, Source: "files"},
-	{Name: "tree_entry_mode", Type: sql.Text, Source: "files"},
+	{Name: "blob_hash", Type: sql.VarChar(40), Source: "files"},
+	{Name: "tree_hash", Type: sql.VarChar(40), Source: "files"},
+	{Name: "tree_entry_mode", Type: sql.VarChar(16), Source: "files"},
 	{Name: "blob_content", Type: sql.Blob, Source: "files"},
 	{Name: "blob_size", Type: sql.Int64, Source: "files"},
 }
diff --git a/go.mod b/go.mod
index b7b918d79..660ecfedd 100644
--- a/go.mod
+++ b/go.mod
@@ -2,6 +2,8 @@ module github.com/src-d/gitbase
 
 go 1.12
 
+replace github.com/src-d/go-mysql-server => /home/juanjux/sourced/go-mysql-server.v0
+
 require (
 	github.com/bblfsh/go-client/v4 v4.1.0
 	github.com/bblfsh/sdk/v3 v3.1.0
diff --git a/ref_commits.go b/ref_commits.go
index 8bd10fd21..c39d48c63 100644
--- a/ref_commits.go
+++ b/ref_commits.go
@@ -22,7 +22,7 @@ type refCommitsTable struct {
 // RefCommitsSchema is the schema for the ref commits table.
 var RefCommitsSchema = sql.Schema{
 	{Name: "repository_id", Type: sql.Text, Source: RefCommitsTableName},
-	{Name: "commit_hash", Type: sql.Text, Source: RefCommitsTableName},
+	{Name: "commit_hash", Type: sql.VarChar(40), Source: RefCommitsTableName},
 	{Name: "ref_name", Type: sql.Text, Source: RefCommitsTableName},
 	{Name: "history_index", Type: sql.Int64, Source: RefCommitsTableName},
 }
diff --git a/references.go b/references.go
index c3887c891..ad7bb54bc 100644
--- a/references.go
+++ b/references.go
@@ -23,7 +23,7 @@ type referencesTable struct {
 var RefsSchema = sql.Schema{
 	{Name: "repository_id", Type: sql.Text, Nullable: false, Source: ReferencesTableName},
 	{Name: "ref_name", Type: sql.Text, Nullable: false, Source: ReferencesTableName},
-	{Name: "commit_hash", Type: sql.Text, Nullable: false, Source: ReferencesTableName},
+	{Name: "commit_hash", Type: sql.VarChar(40), Nullable: false, Source: ReferencesTableName},
 }
 
 func newReferencesTable(pool *RepositoryPool) *referencesTable {
diff --git a/tree_entries.go b/tree_entries.go
index 203a1c2c2..282e833ad 100644
--- a/tree_entries.go
+++ b/tree_entries.go
@@ -22,9 +22,9 @@ type treeEntriesTable struct {
 var TreeEntriesSchema = sql.Schema{
 	{Name: "repository_id", Type: sql.Text, Nullable: false, Source: TreeEntriesTableName},
 	{Name: "tree_entry_name", Type: sql.Text, Nullable: false, Source: TreeEntriesTableName},
-	{Name: "blob_hash", Type: sql.Text, Nullable: false, Source: TreeEntriesTableName},
-	{Name: "tree_hash", Type: sql.Text, Nullable: false, Source: TreeEntriesTableName},
-	{Name: "tree_entry_mode", Type: sql.Text, Nullable: false, Source: TreeEntriesTableName},
+	{Name: "blob_hash", Type: sql.VarChar(40), Nullable: false, Source: TreeEntriesTableName},
+	{Name: "tree_hash", Type: sql.VarChar(40), Nullable: false, Source: TreeEntriesTableName},
+	{Name: "tree_entry_mode", Type: sql.VarChar(16), Nullable: false, Source: TreeEntriesTableName},
 }
 
 func newTreeEntriesTable(pool *RepositoryPool) *treeEntriesTable {