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Track latest topic for each schedule
Track latest topic for each schedule
This adds a new latest_topic_id column to topic_schedule and uses triggers on the topics table to keep it correct. This isn't really ideal, but it will simplify a few things related to scheduled topics by quite a bit. For example, this commit also uses that new data to much more easily populate the list of scheduled topics in a group's sidebar, which previously required a subquery and windowing.merge-requests/106/head
Deimos
4 years ago
5 changed files with 180 additions and 16 deletions
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103tildes/alembic/versions/468cf81f4a6b_topic_schedule_add_latest_topic_id.py
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53tildes/sql/init/triggers/topics/topic_schedule.sql
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5tildes/tildes/models/topic/topic.py
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14tildes/tildes/models/topic/topic_schedule.py
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21tildes/tildes/views/topic.py
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"""topic_schedule: add latest_topic_id |
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Revision ID: 468cf81f4a6b |
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Revises: 4d86b372a8db |
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Create Date: 2020-06-25 02:53:09.435947 |
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""" |
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from alembic import op |
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import sqlalchemy as sa |
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# revision identifiers, used by Alembic. |
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revision = "468cf81f4a6b" |
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down_revision = "4d86b372a8db" |
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branch_labels = None |
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depends_on = None |
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def upgrade(): |
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op.add_column( |
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"topic_schedule", sa.Column("latest_topic_id", sa.Integer(), nullable=True) |
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) |
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op.create_foreign_key( |
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op.f("fk_topic_schedule_latest_topic_id_topics"), |
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"topic_schedule", |
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"topics", |
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["latest_topic_id"], |
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["topic_id"], |
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) |
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op.execute( |
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""" |
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create or replace function update_topic_schedule_latest_topic_id() returns trigger as $$ |
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begin |
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if (NEW.schedule_id is not null) then |
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update topic_schedule |
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set latest_topic_id = ( |
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select topic_id |
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from topics |
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where schedule_id = NEW.schedule_id |
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and is_deleted = false |
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and is_removed = false |
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order by created_time desc limit 1) |
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where schedule_id = NEW.schedule_id; |
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end if; |
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-- if it was an update that changed schedule_id, need to update the old schedule's |
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-- latest_topic_id as well (this will probably be extremely uncommon) |
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if (TG_OP = 'UPDATE' |
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and OLD.schedule_id is not null |
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and OLD.schedule_id is distinct from NEW.schedule_id) then |
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update topic_schedule |
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set latest_topic_id = ( |
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select topic_id |
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from topics |
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where schedule_id = OLD.schedule_id |
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and is_deleted = false |
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and is_removed = false |
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order by created_time desc limit 1) |
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where schedule_id = OLD.schedule_id; |
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end if; |
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return null; |
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end |
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$$ language plpgsql; |
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""" |
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) |
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op.execute( |
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""" |
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create trigger update_topic_schedule_latest_topic_id_insert |
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after insert on topics |
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for each row |
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when (NEW.schedule_id is not null) |
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execute procedure update_topic_schedule_latest_topic_id(); |
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""" |
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) |
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op.execute( |
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""" |
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create trigger update_topic_schedule_latest_topic_id_update |
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after update on topics |
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for each row |
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when ((OLD.schedule_id is not null or NEW.schedule_id is not null) |
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and ((OLD.is_deleted is distinct from NEW.is_deleted) |
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or (OLD.is_removed is distinct from NEW.is_removed) |
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or (OLD.schedule_id is distinct from NEW.schedule_id))) |
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execute procedure update_topic_schedule_latest_topic_id(); |
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""" |
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) |
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def downgrade(): |
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op.execute("drop trigger update_topic_schedule_latest_topic_id_update on topics") |
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op.execute("drop trigger update_topic_schedule_latest_topic_id_insert on topics") |
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op.execute("drop function update_topic_schedule_latest_topic_id") |
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op.drop_constraint( |
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op.f("fk_topic_schedule_latest_topic_id_topics"), |
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"topic_schedule", |
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type_="foreignkey", |
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) |
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op.drop_column("topic_schedule", "latest_topic_id") |
@ -0,0 +1,53 @@ |
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-- Copyright (c) 2020 Tildes contributors <code@tildes.net> |
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-- SPDX-License-Identifier: AGPL-3.0-or-later |
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create or replace function update_topic_schedule_latest_topic_id() returns trigger as $$ |
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begin |
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if (NEW.schedule_id is not null) then |
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update topic_schedule |
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set latest_topic_id = ( |
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select topic_id |
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from topics |
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where schedule_id = NEW.schedule_id |
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and is_deleted = false |
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and is_removed = false |
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order by created_time desc limit 1) |
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where schedule_id = NEW.schedule_id; |
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end if; |
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|
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-- if it was an update that changed schedule_id, need to update the old schedule's |
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-- latest_topic_id as well (this will probably be extremely uncommon) |
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if (TG_OP = 'UPDATE' |
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and OLD.schedule_id is not null |
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and OLD.schedule_id is distinct from NEW.schedule_id) then |
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update topic_schedule |
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set latest_topic_id = ( |
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select topic_id |
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from topics |
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where schedule_id = OLD.schedule_id |
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and is_deleted = false |
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and is_removed = false |
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order by created_time desc limit 1) |
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where schedule_id = OLD.schedule_id; |
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end if; |
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return null; |
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end |
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$$ language plpgsql; |
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create trigger update_topic_schedule_latest_topic_id_insert |
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after insert on topics |
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for each row |
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when (NEW.schedule_id is not null) |
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execute procedure update_topic_schedule_latest_topic_id(); |
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|
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create trigger update_topic_schedule_latest_topic_id_update |
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after update on topics |
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for each row |
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when ((OLD.schedule_id is not null or NEW.schedule_id is not null) |
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and ((OLD.is_deleted is distinct from NEW.is_deleted) |
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or (OLD.is_removed is distinct from NEW.is_removed) |
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or (OLD.schedule_id is distinct from NEW.schedule_id))) |
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execute procedure update_topic_schedule_latest_topic_id(); |
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