stuff

crates/db_schema/src/schema_setup.rs

@@ -60,12 +60,13 @@ fn replaceable_schema() -> String {
 
 const REPLACEABLE_SCHEMA_PATH: &str = "crates/db_schema/replaceable_schema";
 
-struct MigrationHarnessWrapper<'a, 'b> {
+struct MigrationHarnessWrapper<'a> {
   conn: &'a mut PgConnection,
-  options: &'b Options,
+  #[cfg(test)]
+  enable_diff_check: bool,
 }
 
-impl<'a, 'b> MigrationHarnessWrapper<'a, 'b> {
+impl<'a> MigrationHarnessWrapper<'a> {
   fn run_migration_inner(
     &mut self,
     migration: &dyn Migration<Pg>,
@@ -82,13 +83,13 @@ impl<'a, 'b> MigrationHarnessWrapper<'a, 'b> {
   }
 }
 
-impl<'a, 'b> MigrationHarness<Pg> for MigrationHarnessWrapper<'a, 'b> {
+impl<'a> MigrationHarness<Pg> for MigrationHarnessWrapper<'a> {
   fn run_migration(
     &mut self,
     migration: &dyn Migration<Pg>,
   ) -> diesel::migration::Result<MigrationVersion<'static>> {
     #[cfg(test)]
-    if self.options.enable_diff_check {
+    if self.enable_diff_check {
       let before = diff_check::get_dump();
 
       self.run_migration_inner(migration)?;
@@ -129,71 +130,60 @@ impl<'a, 'b> MigrationHarness<Pg> for MigrationHarnessWrapper<'a, 'b> {
   }
 }
 
+#[derive(Default)]
 pub struct Options {
-  enable_forbid_diesel_cli_trigger: bool,
+  #[cfg(test)]
   enable_diff_check: bool,
   revert: bool,
   run: bool,
-  amount: Option<u64>,
+  limit: Option<u64>,
-}
-
-impl Default for Options {
-  fn default() -> Self {
-    Options {
-      enable_forbid_diesel_cli_trigger: false,
-      enable_diff_check: false,
-      revert: false,
-      run: true,
-      amount: None,
-    }
-  }
 }
 
 impl Options {
-  #[cfg(test)]
-  fn enable_forbid_diesel_cli_trigger(mut self) -> Self {
-    self.enable_forbid_diesel_cli_trigger = true;
-    self
-  }
-
   #[cfg(test)]
   fn enable_diff_check(mut self) -> Self {
     self.enable_diff_check = true;
     self
   }
 
-  pub fn revert(mut self, amount: Option<u64>) -> Self {
+  pub fn run(mut self) -> Self {
-    self.revert = true;
-    self.run = false;
-    self.amount = amount;
-    self
-  }
-
-  pub fn redo(mut self, amount: Option<u64>) -> Self {
-    self.revert = true;
     self.run = true;
-    self.amount = amount;
+    self
+  }
+
+  pub fn revert(mut self) -> Self {
+    self.revert = true;
+    self
+  }
+
+  pub fn limit(mut self, limit: u64) -> Self {
+    self.limit = Some(limit);
     self
   }
 }
 
-// TODO return struct with field `ran_replaceable_schema`
+/// Checked by tests
-pub fn run(options: Options) -> LemmyResult<()> {
+#[derive(PartialEq, Eq, Debug)]
+pub enum Branch {
+  EarlyReturn,
+  ReplaceableSchemaRebuilt,
+  ReplaceableSchemaNotRebuilt,
+}
+
+pub fn run(options: Options) -> LemmyResult<Branch> {
   let db_url = SETTINGS.get_database_url();
 
   // Migrations don't support async connection, and this function doesn't need to be async
-  //let mut conn = PgConnection::establish(&db_url).context("Error connecting to database")?;
   let mut conn = PgConnection::establish(&db_url)?;
 
-  // If possible, skip locking the migrations table and recreating the "r" schema, so
+  // If possible, skip getting a lock and recreating the "r" schema, so
   // lemmy_server processes in a horizontally scaled setup can start without causing locks
   if !options.revert
     && options.run
-    && options.amount.is_none()
+    && options.limit.is_none()
     && !conn
       .has_pending_migration(migrations())
       .map_err(convert_err)?
-  //.map_err(|e| anyhow!("Couldn't check pending migrations: {e}"))?)
   {
     // The condition above implies that the migration that creates the previously_run_sql table was already run
     let sql_unchanged = exists(
@@ -203,19 +193,14 @@ pub fn run(options: Options) -> LemmyResult<()> {
     let schema_exists = exists(pg_namespace::table.find("r"));
 
     if select(sql_unchanged.and(schema_exists)).get_result(&mut conn)? {
-      return Ok(());
+      return Ok(Branch::EarlyReturn);
     }
   }
 
-  // Disable the trigger that prevents the Diesel CLI from running migrations
+  // Block concurrent attempts to run migrations until `conn` is closed, and disable the
-  if !options.enable_forbid_diesel_cli_trigger {
+  // trigger that prevents the Diesel CLI from running migrations
-    conn.batch_execute("SET lemmy.enable_migrations TO 'on';")?;
-  }
-
-  // Block concurrent attempts to run migrations (lock is automatically released at the end
-  // because the connection is not reused)
   info!("Waiting for lock...");
-  conn.batch_execute("SELECT pg_advisory_lock(0)")?;
+  conn.batch_execute("SELECT pg_advisory_lock(0);")?;
   info!("Running Database migrations (This may take a long time)...");
 
   // Drop `r` schema, so migrations don't need to be made to work both with and without things in
@@ -225,7 +210,7 @@ pub fn run(options: Options) -> LemmyResult<()> {
   run_selected_migrations(&mut conn, &options).map_err(convert_err)?;
 
   // Only run replaceable_schema if newest migration was applied
-  if (options.run && options.amount.is_none())
+  let output = if (options.run && options.limit.is_none())
     || !conn
       .has_pending_migration(migrations())
       .map_err(convert_err)?
@@ -243,11 +228,15 @@ pub fn run(options: Options) -> LemmyResult<()> {
     }
 
     run_replaceable_schema(&mut conn)?;
-  }
+
+    Branch::ReplaceableSchemaRebuilt
+  } else {
+    Branch::ReplaceableSchemaNotRebuilt
+  };
 
   info!("Database migrations complete.");
 
-  Ok(())
+  Ok(output)
 }
 
 fn run_replaceable_schema(conn: &mut PgConnection) -> LemmyResult<()> {
@@ -281,11 +270,15 @@ fn run_selected_migrations(
   conn: &mut PgConnection,
   options: &Options,
 ) -> diesel::migration::Result<()> {
-  let mut wrapper = MigrationHarnessWrapper { conn, options };
+  let mut wrapper = MigrationHarnessWrapper {
+    conn,
+    #[cfg(test)]
+    enable_diff_check: options.enable_diff_check,
+  };
 
   if options.revert {
-    if let Some(amount) = options.amount {
+    if let Some(limit) = options.limit {
-      for _ in 0..amount {
+      for _ in 0..limit {
         wrapper.revert_last_migration(migrations())?;
       }
     } else {
@@ -294,8 +287,8 @@ fn run_selected_migrations(
   }
 
   if options.run {
-    if let Some(amount) = options.amount {
+    if let Some(limit) = options.limit {
-      for _ in 0..amount {
+      for _ in 0..limit {
         wrapper.run_next_migration(migrations())?;
       }
     } else {
@@ -307,19 +300,24 @@ fn run_selected_migrations(
 }
 
 /// Makes `diesel::migration::Result` work with `anyhow` and `LemmyError`
-fn convert_err(
+fn convert_err(e: Box<dyn std::error::Error + Send + Sync>) -> anyhow::Error {
-  err: Box<dyn std::error::Error + Send + Sync>,
+  anyhow!(e)
-  //) -> impl std::error::Error + Send + Sync + 'static {
-) -> anyhow::Error {
-  anyhow::anyhow!(err)
 }
 
 #[cfg(test)]
 mod tests {
-  use super::*;
+  use super::{
+    Branch::{EarlyReturn, ReplaceableSchemaNotRebuilt, ReplaceableSchemaRebuilt},
+    *,
+  };
   use lemmy_utils::{error::LemmyResult, settings::SETTINGS};
   use serial_test::serial;
 
+  /// Reduces clutter
+  fn o() -> Options {
+    Options::default()
+  }
+
   #[test]
   #[serial]
   fn test_schema_setup() -> LemmyResult<()> {
@@ -329,18 +327,37 @@ mod tests {
     // Start with consistent state by dropping everything
     conn.batch_execute("DROP OWNED BY CURRENT_USER;")?;
 
-    // Check for mistakes in down.sql files
+    // Run all migrations and check for mistakes in down.sql files
-    run(Options::default().enable_diff_check())?;
+    assert_eq!(
+      run(o().run().enable_diff_check())?,
+      ReplaceableSchemaRebuilt
+    );
 
-    // TODO also don't drop r, and maybe just directly call the migrationharness method here
+    // Check for early return
-    run(Options::default().revert(None))?;
+    assert_eq!(run(o().run())?, EarlyReturn);
+
+    // Test `limit`
+    assert_eq!(run(o().revert().limit(1))?, ReplaceableSchemaNotRebuilt);
+    assert_eq!(
+      conn
+        .pending_migrations(migrations())
+        .map_err(convert_err)?
+        .len(),
+      1
+    );
+    assert_eq!(run(o().run().limit(1))?, ReplaceableSchemaRebuilt);
+
+    // Revert all migrations
+    assert_eq!(run(o().revert())?, ReplaceableSchemaNotRebuilt);
+
+    // This should throw an error saying to use lemmy_server instead of diesel CLI
     assert!(matches!(
-      run(Options::default().enable_forbid_diesel_cli_trigger()),
+      conn.run_pending_migrations(migrations()),
       Err(e) if e.to_string().contains("lemmy_server")
     ));
 
-    // Previous run shouldn't stop this one from working
+    // Diesel CLI's way of running migrations shouldn't break the custom migration runner
-    run(Options::default())?;
+    assert_eq!(run(o().run())?, ReplaceableSchemaRebuilt);
 
     Ok(())
   }

crates/db_schema/src/schema_setup/diff_check.rs

@@ -1,7 +1,7 @@
 use lemmy_utils::settings::SETTINGS;
 use std::{
   borrow::Cow,
-  collections::BTreeSet,
+  collections::btree_set::{self, BTreeSet},
   fmt::Write,
   process::{Command, Stdio},
 };
@@ -36,28 +36,203 @@ pub fn get_dump() -> String {
 const PATTERN_LEN: usize = 19;
 
 pub fn check_dump_diff(mut after: String, mut before: String, label: &str) {
+  // Performance optimization
   if after == before {
     return;
   }
-  // Ignore timestamp differences by removing timestamps
+
-  for dump in [&mut before, &mut after] {
+  let normalized_chunk_vecs = [&before, &after]
+    // Remove identical items
+    .map(|dump| chunks(dump).collect::<BTreeSet<_>>())
+    .differences()
+    // Remove items without unwanted types of differences (if migrations are correct, then this removes everything)
+    .map(|chunks| {
+      chunks.map(|&i| normalize_chunk(i)).collect::<BTreeSet<_>>()
+    });
+
+  let [mut only_in_before, mut only_in_after] = normalized_chunk_vecs
+    .differences()
+    .map(|chunks| chunks.map(|i| &**i).collect::<Vec<_>>());
+
+  if only_in_before.is_empty() && only_in_after.is_empty() {
+    return;
+  }
+
+  // Build the panic message
+
+  let after_has_more = only_in_before.len() < only_in_after.len();
+  let [mut chunks, mut other_chunks] = if after_has_more {
+    [only_in_before, only_in_after]
+  } else {
+    [only_in_after, only_in_before]
+  };
+
+  let diffs = chunks
+    .into_iter()
+    .chain(std::iter::repeat(""))
+    .map_while(|chunk| {
+      let (most_similar_chunk_index, most_similar_chunk) = other_chunks
+        .iter()
+        .enumerate()
+        .max_by_key(|(_, other_chunk)| {
+          if sql_command_name(&chunk) != sql_command_name(&other_chunk) {
+            0
+          } else {
+            similarity(&chunk, &other_chunk)
+          }
+        })?;
+
+      let lines = if after_has_more {
+        diff::lines(most_similar_chunk, &chunk)
+      } else {
+        diff::lines(&chunk, most_similar_chunk)
+      };
+
+      other_chunks.swap_remove(most_similar_chunk_index);
+
+      Some(
+        lines
+          .into_iter()
+          .map(|line| {
+            Cow::Owned(match line {
+              diff::Result::Left(s) => format!("- {s}\n"),
+              diff::Result::Right(s) => format!("+ {s}\n"),
+              diff::Result::Both(s, _) => format!("  {s}\n"),
+            })
+          })
+          .chain([Cow::Borrowed("\n")])
+          .collect::<String>(),
+      )
+    });
+
+  panic!(
+    "{}",
+    std::iter::once(format!("{label}\n\n"))
+      .chain(diffs)
+      .collect::<String>()
+  );
+}
+
+trait Differences<T> {
+  fn differences(&self) -> [btree_set::Difference<'_, T>; 2];
+}
+
+impl<T: Ord> Differences<T> for [BTreeSet<T>; 2] {
+  /// Items only in `a`, and items only in `b`
+  fn differences(&self) -> [btree_set::Difference<'_, T>; 2] {
+    let [a, b] = self;
+    [a.difference(&b), b.difference(&a)]
+  }
+}
+
+fn sql_command_name(chunk: &str) -> &str {
+  chunk
+    .split_once(|c: char| c.is_lowercase())
+    .unwrap_or_default()
+    .0
+}
+
+fn similarity(chunk: &str, other_chunk: &str) -> usize {
+  diff::chars(chunk, other_chunk)
+    .into_iter()
+    .filter(|i| {
+      match i {
+        diff::Result::Both(c, _) => {
+          // Prevent whitespace from affecting similarity level
+          !c.is_whitespace()
+            && (
+              // Increase accuracy for some trigger function diffs
+              c.is_lowercase()
+                  // Preserve differences in names that contain a number
+                  || c.is_numeric()
+            )
+        }
+        _ => false,
+      }
+    })
+    .count()
+}
+
+fn normalize_chunk<'a>(chunk: &'a str) -> Cow<'a, str> {
+  let mut chunk = Cow::Borrowed(chunk);
+
+  let stripped_lines = chunk
+    .lines()
+    .map(|line| line.strip_suffix(',').unwrap_or(line));
+
+  // Sort column names, so differences in column order are ignored
+  if chunk.starts_with("CREATE TABLE ") {
+    let mut lines = stripped_lines.collect::<Vec<_>>();
+
+    sort_within_sections(&mut lines, |line| {
+      match line.chars().next() {
+        // CREATE
+        Some('C') => 0,
+        // Indented column name
+        Some(' ') => 1,
+        // End
+        Some(')') => 2,
+        _ => panic!("unrecognized part of `CREATE TABLE` statement: {line}"),
+      }
+    });
+
+    chunk = Cow::Owned(lines.join("\n"));
+  } else if chunk.starts_with("CREATE VIEW ") || chunk.starts_with("CREATE OR REPLACE VIEW ") {
+    let is_simple_select_statement = chunk.lines().enumerate().all(|(i, line)| {
+      match (i, line.trim_start().chars().next()) {
+        // CREATE
+        (0, Some('C')) => true,
+        // SELECT
+        (1, Some('S')) => true,
+        // FROM
+        (_, Some('F')) if line.ends_with(';') => true,
+        // Column name
+        (_, Some(c)) if c.is_lowercase() => true,
+        _ => false,
+      }
+    });
+
+    if is_simple_select_statement {
+      let mut lines = stripped_lines.collect::<Vec<_>>();
+
+      sort_within_sections(&mut lines, |line| {
+        match line.trim_start().chars().next() {
+          // CREATE
+          Some('C') => 0,
+          // SELECT
+          Some('S') => 1,
+          // FROM
+          Some('F') => 3,
+          // Column name
+          _ => 2,
+        }
+      });
+
+      chunk = Cow::Owned(lines.join("\n"));
+    }
+  }
+
+  // Replace timestamps with a constant string, so differences in timestamps are ignored
   for index in 0.. {
-      let Some(byte) = dump.as_bytes().get(index) else {
+    // Performance optimization
+    let Some(byte) = chunk.as_bytes().get(index) else {
       break;
     };
     if !byte.is_ascii_digit() {
       continue;
     }
+
     // Check for this pattern: 0000-00-00 00:00:00
     let Some((
       &[a0, a1, a2, a3, b0, a4, a5, b1, a6, a7, b2, a8, a9, b3, a10, a11, b4, a12, a13],
       remaining,
-      )) = dump
+    )) = chunk
       .get(index..)
       .and_then(|s| s.as_bytes().split_first_chunk::<PATTERN_LEN>())
     else {
       break;
     };
+
     if [a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13]
       .into_iter()
       .all(|byte| byte.is_ascii_digit())
@@ -70,162 +245,19 @@ pub fn check_dump_diff(mut after: String, mut before: String, label: &str) {
         0
       };
       // Length of replacement string is likely to match previous string
-        // (usually there's up to 6 digits after the decimal point)
+      // (there's up to 6 digits after the decimal point)
-        dump.replace_range(
+      chunk.to_mut().replace_range(
         index..(index + PATTERN_LEN + len_after),
         "AAAAAAAAAAAAAAAAAAAAAAAAAA",
       );
     }
   }
+
+  chunk
 }
 
-  let [before_chunks, after_chunks] =
+fn sort_within_sections<T: Ord + ?Sized>(vec: &mut Vec<&T>, mut section: impl FnMut(&T) -> u8) {
-    [&before, &after].map(|dump| chunks(dump).collect::<BTreeSet<_>>());
+  vec.sort_unstable_by_key(|&i|(section(i),i));
-  let only_b = before_chunks
-    .difference(&after_chunks)
-    .copied()
-    .map(process_chunk)
-    .collect::<BTreeSet<_>>();
-  let only_a = after_chunks
-    .difference(&before_chunks)
-    .copied()
-    .map(process_chunk)
-    .collect::<BTreeSet<_>>();
-
-  // todo dont collect only_in_before?
-  let [mut only_in_before, mut only_in_after] =
-    [only_b.difference(&only_a), only_a.difference(&only_b)].map(|chunks| {
-      chunks
-        .map(|chunk| {
-          (
-            &**chunk,
-            // Used for ignoring formatting differences, especially indentation level, when
-            // determining which item in `only_in_before` corresponds to which item in `only_in_after`
-            chunk.replace([' ', '\t', '\r', '\n'], ""),
-          )
-        })
-        .collect::<Vec<_>>()
-    });
-  if only_in_before.is_empty() && only_in_after.is_empty() {
-    return;
-  }
-  let after_has_more = only_in_before.len() < only_in_after.len();
-  // outer iterator in the loop below should not be the one with empty strings, otherwise the empty strings
-  // would be equally similar to any other chunk
-  let (chunks_gt, chunks_lt) = if after_has_more {
-    only_in_before.resize_with(only_in_after.len(), Default::default);
-    (&mut only_in_after, &only_in_before)
-  } else {
-    only_in_after.resize_with(only_in_before.len(), Default::default);
-    (&mut only_in_before, &only_in_after)
-  };
-
-  let mut output = label.to_owned();
-  // todo rename variables
-  for (before_chunk, before_chunk_filtered) in chunks_lt {
-    let default = Default::default();
-    //panic!("{:?}",(before_chunk.clone(),chunks_lt.clone()));
-    let (most_similar_chunk_index, (most_similar_chunk, _)) = chunks_gt
-      .iter()
-      .enumerate()
-      .max_by_key(|(_, (after_chunk, after_chunk_filtered))| {
-        if after_chunk
-          .split_once(|c: char| c.is_lowercase())
-          .unwrap_or_default()
-          .0
-          != before_chunk
-            .split_once(|c: char| c.is_lowercase())
-            .unwrap_or_default()
-            .0
-        {
-          0
-        } else {
-          diff::chars(after_chunk_filtered, &before_chunk_filtered)
-            .into_iter()
-            .filter(|i| {
-              matches!(i, diff::Result::Both(c, _)
-          // `is_lowercase` increases accuracy for some trigger function diffs
-          if c.is_lowercase() || c.is_numeric())
-            })
-            .count()
-        }
-      })
-      .unwrap_or((0, &default));
-
-    output.push('\n');
-    let lines = if !after_has_more {
-      diff::lines(&before_chunk, most_similar_chunk)
-    } else {
-      diff::lines(most_similar_chunk, &before_chunk)
-    };
-    for line in lines {
-      match line {
-        diff::Result::Left(s) => write!(&mut output, "\n- {s}"),
-        diff::Result::Right(s) => write!(&mut output, "\n+ {s}"),
-        diff::Result::Both(s, _) => write!(&mut output, "\n  {s}"),
-      }
-      .expect("failed to build string");
-    }
-    //write!(&mut output, "\n{most_similar_chunk_filtered}");
-    if !chunks_gt.is_empty() {
-      chunks_gt.swap_remove(most_similar_chunk_index);
-    }
-  }
-  // should have all been removed
-  assert_eq!(chunks_gt.len(), 0);
-  panic!("{output}");
-}
-
-fn process_chunk<'a>(result: &'a str) -> Cow<'a, str> {
-  if result.starts_with("CREATE TABLE ") {
-    // Allow column order to change
-    let mut lines = result
-      .lines()
-      .map(|line| line.strip_suffix(',').unwrap_or(line))
-      .collect::<Vec<_>>();
-    lines.sort_unstable_by_key(|line| -> (u8, &str) {
-      let placement = match line.chars().next() {
-        Some('C') => 0,
-        Some(' ') => 1,
-        Some(')') => 2,
-        _ => panic!("unrecognized part of `CREATE TABLE` statement: {line}"),
-      };
-      (placement, line)
-    });
-    Cow::Owned(lines.join("\n"))
-  } else if result.starts_with("CREATE VIEW") || result.starts_with("CREATE OR REPLACE VIEW") {
-    // Allow column order to change
-    let is_simple_select_statement = result.lines().enumerate().all(|(i, mut line)| {
-      line = line.trim_start();
-      match (i, line.chars().next()) {
-        (0, Some('C')) => true,                        // create
-        (1, Some('S')) => true,                        // select
-        (_, Some('F')) if line.ends_with(';') => true, // from
-        (_, Some(c)) if c.is_lowercase() => true,      // column name
-        _ => false,
-      }
-    });
-    if is_simple_select_statement {
-      let mut lines = result
-        .lines()
-        .map(|line| line.strip_suffix(',').unwrap_or(line))
-        .collect::<Vec<_>>();
-      lines.sort_unstable_by_key(|line| -> (u8, &str) {
-        let placement = match line.trim_start().chars().next() {
-          Some('C') => 0,
-          Some('S') => 1,
-          Some('F') => 3,
-          _ => 2,
-        };
-        (placement, line)
-      });
-      Cow::Owned(lines.join("\n"))
-    } else {
-      Cow::Borrowed(result)
-    }
-  } else {
-    Cow::Borrowed(result)
-  }
 }
 
 fn chunks(dump: &str) -> impl Iterator<Item = &str> {
@@ -235,7 +267,8 @@ fn chunks(dump: &str) -> impl Iterator<Item = &str> {
     while let Some(s) = remove_skipped_item_from_beginning(remaining) {
       remaining = s.trim_start();
     }
-    // `a` can't be empty because of trim_start
+
+    // `trim_start` guarantees that `result` is not empty
     let (result, after_result) = remaining.split_once("\n\n")?;
     remaining = after_result;
     Some(result)
@@ -245,14 +278,18 @@ fn chunks(dump: &str) -> impl Iterator<Item = &str> {
 fn remove_skipped_item_from_beginning(s: &str) -> Option<&str> {
   // Skip commented line
   if let Some(after) = s.strip_prefix("--") {
-    Some(after.split_once('\n').unwrap_or_default().1)
+    Some(after_first_occurence(after, "\n"))
   }
   // Skip view definition that's replaced later (the first definition selects all nulls)
   else if let Some(after) = s.strip_prefix("CREATE VIEW ") {
     let (name, after_name) = after.split_once(' ').unwrap_or_default();
-    Some(after_name.split_once("\n\n").unwrap_or_default().1)
+    Some(after_first_occurence(after_name, "\n\n"))
       .filter(|after_view| after_view.contains(&format!("\nCREATE OR REPLACE VIEW {name} ")))
   } else {
     None
   }
 }
+
+fn after_first_occurence<'a>(s: &'a str, pat: &str) -> &'a str {
+  s.split_once(pat).unwrap_or_default().1
+}

crates/db_schema/src/utils.rs

@@ -1,4 +1,4 @@
-use crate::{newtypes::DbUrl, CommentSortType, SortType};
+use crate::{newtypes::DbUrl, CommentSortType, SortType,schema_setup};
 use chrono::{DateTime, TimeDelta, Utc};
 use deadpool::Runtime;
 use diesel::{
@@ -427,7 +427,7 @@ pub async fn build_db_pool() -> LemmyResult<ActualDbPool> {
     }))
     .build()?;
 
-  crate::schema_setup::run(Default::default())?;
+  schema_setup::run(schema_setup::Options::default().run())?;
 
   Ok(pool)
 }

migrations/2020-04-14-163701_update_views_for_activitypub/down.sql

@@ -287,7 +287,8 @@ DROP VIEW post_aggregates_view;
 
 -- regen post view
 CREATE VIEW post_aggregates_view AS
-SELECT p.id,
+SELECT
+    p.id,
     p.name,
     p.url,
     p.body,

migrations/2020-06-30-135809_remove_mat_views/down.sql

@@ -1014,7 +1014,7 @@ BEGIN
 END
 $$;
 
-CREATE or replace TRIGGER refresh_community_follower
+CREATE OR REPLACE TRIGGER refresh_community_follower
     AFTER INSERT OR UPDATE OR DELETE OR TRUNCATE ON community_follower
     FOR EACH statement
     EXECUTE PROCEDURE refresh_community_follower ();
@@ -1031,7 +1031,7 @@ BEGIN
 END
 $$;
 
-CREATE or replace TRIGGER refresh_community_user_ban
+CREATE OR REPLACE TRIGGER refresh_community_user_ban
     AFTER INSERT OR UPDATE OR DELETE OR TRUNCATE ON community_user_ban
     FOR EACH statement
     EXECUTE PROCEDURE refresh_community_user_ban ();
@@ -1048,12 +1048,12 @@ BEGIN
 END
 $$;
 
-CREATE or replace TRIGGER refresh_post_like
+CREATE OR REPLACE TRIGGER refresh_post_like
     AFTER INSERT OR UPDATE OR DELETE OR TRUNCATE ON post_like
     FOR EACH statement
     EXECUTE PROCEDURE refresh_post_like ();
 
-CREATE or replace VIEW community_moderator_view AS
+CREATE OR REPLACE VIEW community_moderator_view AS
 SELECT
     *,
     (
@@ -1107,7 +1107,7 @@ SELECT
 FROM
     community_moderator cm;
 
-CREATE or replace VIEW community_follower_view AS
+CREATE OR REPLACE VIEW community_follower_view AS
 SELECT
     *,
     (
@@ -1161,7 +1161,7 @@ SELECT
 FROM
     community_follower cf;
 
-CREATE or replace VIEW community_user_ban_view AS
+CREATE OR REPLACE VIEW community_user_ban_view AS
 SELECT
     *,
     (

migrations/2021-03-09-171136_split_user_table_2/down.sql

@@ -241,7 +241,8 @@ ALTER TABLE user_
     ADD COLUMN matrix_user_id text UNIQUE;
 
 -- Default is only for existing rows
-alter table user_ alter column password_encrypted drop default;
+ALTER TABLE user_
+    ALTER COLUMN password_encrypted DROP DEFAULT;
 
 -- Update the user_ table with the local_user data
 UPDATE

migrations/2023-02-05-102549_drop-site-federation-debug/down.sql

@@ -1,3 +1,3 @@
 ALTER TABLE local_site
-    ADD COLUMN federation_debug boolean DEFAULT false not null;
+    ADD COLUMN federation_debug boolean DEFAULT FALSE NOT NULL;
 

migrations/2023-08-23-182533_scaled_rank/down.sql

@@ -86,10 +86,7 @@ ALTER TABLE local_user
 DROP TYPE sort_type_enum__;
 
 -- Remove int to float conversions that were automatically added to index filters
-DROP INDEX
+DROP INDEX idx_comment_aggregates_nonzero_hotrank, idx_community_aggregates_nonzero_hotrank, idx_post_aggregates_nonzero_hotrank;
-idx_comment_aggregates_nonzero_hotrank,
-idx_community_aggregates_nonzero_hotrank,
-idx_post_aggregates_nonzero_hotrank;
 
 CREATE INDEX idx_community_aggregates_nonzero_hotrank ON community_aggregates (published)
 WHERE

migrations/2024-04-29-012112_forbid_diesel_cli/up.sql

@@ -16,7 +16,11 @@ CREATE FUNCTION forbid_diesel_cli ()
     LANGUAGE plpgsql
     AS $$
 BEGIN
-    IF current_setting('lemmy.enable_migrations', TRUE) IS DISTINCT FROM 'on' THEN
+    IF NOT EXISTS (
+        SELECT
+        FROM
+            pg_locks
+        WHERE (locktype, pid, objid) = ('advisory', pg_backend_pid(), 0)) THEN
 RAISE 'migrations must be managed using lemmy_server instead of diesel CLI';
 END IF;
     RETURN NULL;

src/lib.rs

@@ -114,13 +114,19 @@ enum CmdSubcommand {
   Migration {
     #[command(subcommand)]
     subcommand: MigrationSubcommand,
+    #[arg(short, long, conflicts_with("number"))]
+    all: bool,
+    #[arg(short, long, default_value_t = 1)]
+    number: u64,
   },
 }
 
 #[derive(Subcommand, Debug)]
 enum MigrationSubcommand {
-  /// Run all pending migrations.
+  /// Run up.sql for the specified migrations.
   Run,
+  /// Run down.sql for the specified migrations.
+  Revert,
 }
 
 /// Placing the main function in lib.rs allows other crates to import it and embed Lemmy
@@ -128,11 +134,22 @@ pub async fn start_lemmy_server(args: CmdArgs) -> LemmyResult<()> {
   // Print version number to log
   println!("Lemmy v{VERSION}");
 
-  if let Some(CmdSubcommand::Migration { subcommand }) = args.subcommand {
+  // todo test
-    let options = match subcommand {
+  if let Some(CmdSubcommand::Migration {
-      MigrationSubcommand::Run => schema_setup::Options::default(),
+    subcommand,
+    all,
+    number,
+  }) = args.subcommand
+  {
+    let mut options = match subcommand {
+      MigrationSubcommand::Run => schema_setup::Options::default().run(),
+      MigrationSubcommand::Revert => schema_setup::Options::default().revert(),
     };
 
+    if !all {
+      options = options.limit(number);
+    }
+
     schema_setup::run(options)?;
 
     return Ok(());