Crate sql_support

A crate with various sql/sqlcipher helpers.

Modules

• debug_tools
• open_database

Structs

• Conn
• LazyDb
  Lazily-loaded database with interruption support
• RepeatDisplay
  Helper type for printing repeated strings more efficiently. You should use repeat_display or one of the repeat_sql_* helpers to construct it.
• UncheckedTransaction
  rusqlite, in an attempt to save us from ourselves, needs a mutable ref to a connection to start a transaction. That is a bit of a PITA in some cases, so we offer this as an alternative - but the responsibility of ensuring there are no concurrent transactions is on our head.

Enums

• MaybeCached
  MaybeCached is a type that can be used to help abstract over cached and uncached rusqlite statements in a transparent manner.

Traits

• ConnExt
  This trait exists so that we can use these helpers on rusqlite::{Transaction, Connection}. Note that you must import ConnExt in order to call these methods on anything.

Functions

• default_max_variable_number
  Returns SQLITE_LIMIT_VARIABLE_NUMBER as read from an in-memory connection and cached. connection and cached. That means this will return the wrong value if it’s set to a lower value for a connection using this will return the wrong thing, but doing so is rare enough that we explicitly don’t support it (why would you want to lower this at runtime?).
• each_chunk
  Helper for the case where you have a &[impl ToSql] of arbitrary length, but need one of no more than the connection’s MAX_VARIABLE_NUMBER (rather, default_max_variable_number()). This is useful when performing batched updates.
• each_chunk_mapped
  A version of each_chunk for the case when the conversion to to_sql requires an custom intermediate step. For example, you might want to grab a property off of an arrray of records
• each_sized_chunk
• each_sized_chunk_mapped
  Utility to help perform batched updates, inserts, queries, etc. This is the low-level version of this utility which is wrapped by each_chunk and each_chunk_mapped, and it allows you to provide both the mapping function, and the chunk size.
• escape_string_for_pragma
  In PRAGMA foo=‘bar’, 'bar' must be a constant string (it cannot be a bound parameter), so we need to escape manually. According to https://www.sqlite.org/faq.html, the only character that must be escaped is the single quote, which is escaped by placing two single quotes in a row.
• repeat_display
  Construct a RepeatDisplay that will repeatedly call fmt_one with a formatter count times, separated by sep.
• repeat_multi_values
  Returns a value that formats as num_values instances of (?,?,?,...) (where there are vars_per_value question marks separated by commas in between the ?s).
• repeat_sql_values
  Returns a value that formats as count instances of (?) separated by commas.
• repeat_sql_vars
  Returns a value that formats as count instances of ? separated by commas.