db-dump: set sequence values when importing a database dump

By default, the import script recreates the database schema, which
includes creating new sequences with zero values. This results in the
lazy crates.io developer occasionally receiving obscure errors when
inserting records into tables that use sequences, often not on the first
or second insert due to IDs in the database dump not always being
continuous.

Rather than dumping the real sequence values from the database, we can
just recreate them based on the maximum ID in each table. Works well
enough, and means we don't have to tinker with the export script or ship
extra data.

This commit only configures the database tables that actually include
data in the database dump. There are other sequences, but since those
tables won't have data imported, it doesn't matter if they remain zero
after import.

crates/crates_io_database_dump/src/configuration.rs

@@ -1,4 +1,4 @@
-use serde::Deserialize;
+use serde::{Deserialize, Serialize};
 use std::collections::{BTreeMap, VecDeque};
 
 /// An enum indicating whether a column is included in the database dumps.
@@ -15,7 +15,9 @@ pub enum ColumnVisibility {
 /// and should list all tables the current tables refers to with foreign key
 /// constraints on public columns. The `filter` field is a valid SQL expression
 /// used in a `WHERE` clause to filter the rows of the table. The `columns`
-/// field maps column names to their respective visibilities.
+/// field maps column names to their respective visibilities. The `sequence`
+/// field, if present, defines the sequence used by the table when generating
+/// IDs, along with the ID column.
 #[derive(Clone, Debug, Default, Deserialize)]
 pub struct TableConfig {
     #[serde(default)]
@@ -24,6 +26,13 @@ pub struct TableConfig {
     pub columns: BTreeMap<String, ColumnVisibility>,
     #[serde(default)]
     pub column_defaults: BTreeMap<String, String>,
+    pub sequence: Option<SequenceConfig>,
+}
+
+#[derive(Clone, Debug, Default, Deserialize, Serialize)]
+pub struct SequenceConfig {
+    pub column: String,
+    pub name: String,
 }
 
 /// Maps table names to the respective configurations. Used to load `dump_db.toml`.

crates/crates_io_database_dump/src/dump-db.toml

@@ -48,6 +48,9 @@ description = "public"
 crates_cnt = "public"
 created_at = "public"
 path = "public"
+[categories.sequence]
+column = "id"
+name = "categories_id_seq"
 
 [crate_downloads.columns]
 crate_id = "public"
@@ -87,6 +90,9 @@ textsearchable_index_col = "private" # This Postgres specific and can be derived
 repository = "public"
 max_upload_size = "public"
 max_features = "public"
+[crates.sequence]
+column = "id"
+name = "packages_id_seq"
 
 [crates_categories]
 dependencies = ["categories", "crates"]
@@ -130,6 +136,9 @@ features = "public"
 target = "public"
 kind = "public"
 explicit_name = "public"
+[dependencies.sequence]
+column = "id"
+name = "dependencies_id_seq"
 
 [__diesel_schema_migrations.columns]
 version = "private"
@@ -152,6 +161,9 @@ id = "public"
 keyword = "public"
 crates_cnt = "public"
 created_at = "public"
+[keywords.sequence]
+column = "id"
+name = "keywords_id_seq"
 
 [metadata.columns]
 total_downloads = "public"
@@ -186,6 +198,9 @@ github_id = "public"
 name = "public"
 avatar = "public"
 org_id = "public"
+[teams.sequence]
+column = "id"
+name = "teams_id_seq"
 
 [users]
 filter = """
@@ -207,6 +222,9 @@ is_admin = "private"
 publish_notifications = "private"
 [users.column_defaults]
 gh_access_token = "''"
+[users.sequence]
+column = "id"
+name = "users_id_seq"
 
 [version_downloads]
 dependencies = ["versions"]
@@ -253,6 +271,9 @@ documentation = "public"
 repository = "public"
 categories = "public"
 keywords = "public"
+[versions.sequence]
+column = "id"
+name = "versions_id_seq"
 
 [versions_published_by.columns]
 version_id = "private"

crates/crates_io_database_dump/src/dump-import.sql.j2

@@ -29,6 +29,19 @@ BEGIN;
 {% for cd in table.column_defaults %}
     ALTER TABLE "{{table.name}}" ALTER COLUMN "{{cd.column}}" DROP DEFAULT;
 {%- endfor %}
+{%- endfor %}
+
+    -- Set sequence values.
+{% for table in tables -%}
+{% if table.sequence %}
+    SELECT setval(
+        '{{table.sequence.name}}',
+        COALESCE(
+            (SELECT MAX("{{table.sequence.column}}") FROM "{{table.name}}")::BIGINT,
+            1
+        )
+    );
+{% endif %}
 {%- endfor %}
 
     -- Reenable triggers on each table.

crates/crates_io_database_dump/src/gen_scripts.rs

@@ -1,4 +1,4 @@
-use crate::configuration::{ColumnVisibility, TableConfig, VisibilityConfig};
+use crate::configuration::{ColumnVisibility, SequenceConfig, TableConfig, VisibilityConfig};
 use anyhow::Context;
 use serde::Serialize;
 use std::{fs::File, path::Path};
@@ -18,6 +18,7 @@ struct HandlebarsTableContext<'a> {
     filter: Option<String>,
     columns: String,
     column_defaults: Vec<ColumnDefault<'a>>,
+    sequence: Option<&'a SequenceConfig>,
 }
 
 #[derive(Debug, Serialize)]