Optimize hot rank updates (#3617)

This commit is contained in:
Sander Saarend 2023-07-17 12:05:55 +03:00 committed by GitHub
parent e9e76549a8
commit 6688a8a5d4
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3 changed files with 30 additions and 22 deletions

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@ -0,0 +1,4 @@
-- This file should undo anything in `up.sql`
DROP INDEX idx_community_aggregates_nonzero_hotrank;
DROP INDEX idx_comment_aggregates_nonzero_hotrank;
DROP INDEX idx_post_aggregates_nonzero_hotrank;

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@ -0,0 +1,4 @@
-- Your SQL goes here
CREATE INDEX idx_community_aggregates_nonzero_hotrank ON community_aggregates (published) WHERE hot_rank != 0;
CREATE INDEX idx_comment_aggregates_nonzero_hotrank ON comment_aggregates (published) WHERE hot_rank != 0;
CREATE INDEX idx_post_aggregates_nonzero_hotrank ON post_aggregates (published DESC) WHERE hot_rank != 0 OR hot_rank_active != 0;

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@ -58,7 +58,7 @@ pub fn setup(
let url = db_url.clone();
scheduler.every(CTimeUnits::minutes(15)).run(move || {
let mut conn = PgConnection::establish(&url).expect("could not establish connection");
update_hot_ranks(&mut conn, true);
update_hot_ranks(&mut conn);
});
// Delete any captcha answers older than ten minutes, every ten minutes
@ -107,7 +107,7 @@ pub fn setup(
fn startup_jobs(db_url: &str) {
let mut conn = PgConnection::establish(db_url).expect("could not establish connection");
active_counts(&mut conn);
update_hot_ranks(&mut conn, false);
update_hot_ranks(&mut conn);
update_banned_when_expired(&mut conn);
clear_old_activities(&mut conn);
overwrite_deleted_posts_and_comments(&mut conn);
@ -115,35 +115,29 @@ fn startup_jobs(db_url: &str) {
/// Update the hot_rank columns for the aggregates tables
/// Runs in batches until all necessary rows are updated once
fn update_hot_ranks(conn: &mut PgConnection, last_week_only: bool) {
let process_start_time = if last_week_only {
info!("Updating hot ranks for last week...");
naive_now() - chrono::Duration::days(7)
} else {
info!("Updating hot ranks for all history...");
NaiveDateTime::from_timestamp_opt(0, 0).expect("0 timestamp creation")
};
fn update_hot_ranks(conn: &mut PgConnection) {
info!("Updating hot ranks for all history...");
process_hot_ranks_in_batches(
conn,
"post_aggregates",
"a.hot_rank != 0 OR a.hot_rank_active != 0",
"SET hot_rank = hot_rank(a.score, a.published),
hot_rank_active = hot_rank(a.score, a.newest_comment_time_necro)",
process_start_time,
);
process_hot_ranks_in_batches(
conn,
"comment_aggregates",
"a.hot_rank != 0",
"SET hot_rank = hot_rank(a.score, a.published)",
process_start_time,
);
process_hot_ranks_in_batches(
conn,
"community_aggregates",
"a.hot_rank != 0",
"SET hot_rank = hot_rank(a.subscribers, a.published)",
process_start_time,
);
info!("Finished hot ranks update!");
@ -155,18 +149,20 @@ struct HotRanksUpdateResult {
published: NaiveDateTime,
}
/// Runs the hot rank update query in batches until all rows after `process_start_time` have been
/// processed.
/// In `set_clause`, "a" will refer to the current aggregates table.
/// Runs the hot rank update query in batches until all rows have been processed.
/// In `where_clause` and `set_clause`, "a" will refer to the current aggregates table.
/// Locked rows are skipped in order to prevent deadlocks (they will likely get updated on the next
/// run)
fn process_hot_ranks_in_batches(
conn: &mut PgConnection,
table_name: &str,
where_clause: &str,
set_clause: &str,
process_start_time: NaiveDateTime,
) {
let process_start_time = NaiveDateTime::from_timestamp_opt(0, 0).expect("0 timestamp creation");
let update_batch_size = 1000; // Bigger batches than this tend to cause seq scans
let mut processed_rows_count = 0;
let mut previous_batch_result = Some(process_start_time);
while let Some(previous_batch_last_published) = previous_batch_result {
// Raw `sql_query` is used as a performance optimization - Diesel does not support doing this
@ -174,7 +170,7 @@ fn process_hot_ranks_in_batches(
let result = sql_query(format!(
r#"WITH batch AS (SELECT a.id
FROM {aggregates_table} a
WHERE a.published > $1
WHERE a.published > $1 AND ({where_clause})
ORDER BY a.published
LIMIT $2
FOR UPDATE SKIP LOCKED)
@ -182,14 +178,18 @@ fn process_hot_ranks_in_batches(
FROM batch WHERE a.id = batch.id RETURNING a.published;
"#,
aggregates_table = table_name,
set_clause = set_clause
set_clause = set_clause,
where_clause = where_clause
))
.bind::<Timestamp, _>(previous_batch_last_published)
.bind::<Integer, _>(update_batch_size)
.get_results::<HotRanksUpdateResult>(conn);
match result {
Ok(updated_rows) => previous_batch_result = updated_rows.last().map(|row| row.published),
Ok(updated_rows) => {
processed_rows_count += updated_rows.len();
previous_batch_result = updated_rows.last().map(|row| row.published);
}
Err(e) => {
error!("Failed to update {} hot_ranks: {}", table_name, e);
break;
@ -197,8 +197,8 @@ fn process_hot_ranks_in_batches(
}
}
info!(
"Finished process_hot_ranks_in_batches execution for {}",
table_name
"Finished process_hot_ranks_in_batches execution for {} (processed {} rows)",
table_name, processed_rows_count
);
}