feat: Eliminate remaining repeat_vars() calls (#6359) #6375
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| for id in msg_ids { | ||
| let ts: i64 = context | ||
| .sql | ||
| .query_get_value("SELECT timestamp FROM msgs WHERE id=?", (id,)) |
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Can be optimized using Sql::call() + preparing a statement and executing it in a loop. But below there's a heavier loop calling Message::load_from_db() anyway
| for &id in &msg_ids { | ||
| if let Some(msg) = context | ||
| .sql | ||
| .query_row_optional( |
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Also can be optimised executing a prepared statement in a loop, but the function is heavy anyway, it creates SMTP jobs etc.
src/receive_imf.rs
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| &format!( | ||
| let trans_fn = |t: &mut rusqlite::Transaction| { | ||
| t.execute( | ||
| "CREATE TABLE contacts_tmp ( |
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Not good that this became a write transaction, but the function call is expected to be heavy anyway if the chat isn't found and an ad-hoc group needs to be created
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Shouldn't it be CREATE TEMPORARY TABLE instead?
SQLite supports this syntax: https://www.sqlite.org/lang_createtable.html
I think it is possible to modify temporary tables with read-only connection as they should not be shared between connections anyway, but this needs to be tested.
Temporary table should still be deleted at the end of transaction because we practically never close connections.
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It works, but requires PRAGMA query_only=0; to be done before creating a temporary table, so there's some "PRAGMA flickering", but i think it's not a problem, anyway temporary tables won't be used frequently it seems
Using `repeat_vars()` to generate SQL statements led to some of them having more than `SQLITE_MAX_VARIABLE_NUMBER` parameters and thus failing, so let's get rid of this pattern. But let's not optimise for now and just repeat executing an SQL statement in a loop, all the places where `repeat_vars()` is used seem not performance-critical and containing functions execute other SQL statements in loops. If needed, performance can be improved by preparing a statement and executing it in a loop. An exception is `lookup_chat_or_create_adhoc_group()` where `repeat_vars()` can't be replaced with a query loop, there we need to replace the `SELECT` query with a read transaction creating a temporary table which is used to perform the SELECT query then.
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