v2.8.0

Upserts are atomic and can write many rows at once. CrudDB.db_upsert now
runs a single INSERT ... ON CONFLICT (...) DO UPDATE statement, which
requires its lookup columns to match a unique constraint: see Breaking
changes below.

Breaking changes

• CrudDB.db_upsert
  requires the columns of filters to match exactly a primary key or unique
  constraint of the table. Upserting on columns without one now fails with
  there is no unique or exclusion constraint matching the ON CONFLICT specification. Filter operators such as score:gt are no longer accepted
  and raise ValueError.
• The filters and data passed to db_upsert must together form a valid
  row to insert, even when the row already exists, since Postgres checks
  NOT NULL constraints before it detects the conflict.
• db_upsert without data updates the existing row to its own key values
  instead of selecting it, so it takes a row lock and fires UPDATE triggers.
• Column onupdate defaults are not applied when db_upsert updates an
  existing row.

New features

• CrudDB.db_upsert_many
  upserts a list of records on the given key columns, in batches of
  batch_size records (1000 by default) within a single transaction. Every
  record must have the same columns and no two records can share a key. See
  the upsert tutorial.