Nagra

**New feature:** Add support for tables without primarey key. No `id`
column is created and the table can not be referenced by other tables.
Usefull for large table like timeseries.

Toml example:

toml
[blog]
natural_key = ["title"]
primary_key = ""
[blog.columns]
title = "text"
length = "int"
user = "bigint"
[blog.foreign_keys]
user = "user"


Python example:

python
Table(
"blog",
columns={
"tile": "text",
"length": "int",
"user": "bigint",
},
natural_key=["title"],
primary_key=None,
foreign_keys={"user": "user"}
)


**New feature:** Add support for tables and columns using reserved
words like `null`, `max` or `select`.

**Fixes:**
- Add support for tables using reserved word like `transaction`, `limit`,
etc.
- Fix returning in with SQLite for tables with custom primary key
(thanks JonathanSamelsonB12).
- Python 3.13, `Transaction.current` is not a property anymore, it is
now a function.

**New feature:** Add `LRUGenerator` for `WriterMixin._resolve`. This will
cache foreign keys resolution within the duration of a transaction. It
has to be enabled through the `fk_cache` parameter when the
transaction is created:

python
with Transaction(dsn, fk_cache=True): default is False
...



It will speed-up upserts (and inserts and updates) when a foreign key
is involved. It shouldn't impact application logic in most
situation. The main corner case is when the `id` value for a given
natural key changes, but this kind of operation is discouraged.


**Various:**
- New `empty` property on `Schema`, return true if no table are present.
- New `sync.py` in `examples/`, demonstrate how to synchonise two
databases with the help of Nagra.
- New `substr`, `isnot` and `match` operators
- Default to `TEXT` instead of `VARCHAR` for string-like column in
Postgresql (improve compatibitly with Timescaledb)
- New `empty` property on `Schema`
- `timestamptz` support in SQLite (thanks cecilehautecoeur)

**New feature:** DB introspection: Nagra is now able to introspect
existing databases and infer schema:

python
from nagra import Transaction, Schema

with Transaction('sqlite://examples/weather/weather.db'):
schema = Schema.from_db()
print(list(schema.tables))
-> ['city', 'weather']

city = schema.get('city')
print(list(city.columns))
-> ['id', 'name']



**New feature:** Temporary suppression of foreign keys constraints. The
`Schema.suspend_fk` context manager is able to drop foreign keys
constraints and re-add them at the end of the block. This allows to
load more complex datasets with cross-references.

**New feature:** The method `Schema.setup_statement` can be used to
generate the simple migration statements without executing them

**Fix** delete with SQLite when a parameter is passed (issue 15)

**Breaking change:** CockroachDB support removed

**Fix** support for '-' operator when only one operand is given

**Fix** `Select.orderby` when multiple expressions are given

**Fix** `Upsert.executemany` when no data is given (empty list)

**Breaking change:** Rename `Schema.load` into `Schema.load_toml`

**New feature:** Cli: Add csv export on select, with `--csv` flag

**Fix:** Add proper quotes around column names on postgresql upsert

**New feature:** Add array support: So one can now declare a table like:

python
parameter_table = Table(
"parameter",
columns={
"name": "str",
"timestamps": "timestamp []",
"values": "float []",
},
natural_key=["name"],
)
upsert = parameter.upsert()
records = [
("one", ["2024-08-03T10:42", "2024-08-03T10:43"], [2, 3]),
("two", ["2024-08-03T10:44", "2024-08-03T10:45"], [4, 5]),
("three", ["2024-08-03T10:46", "2024-08-03T10:47"], [6, 7]),
]
upsert.executemany(records)


**Fix:** Cli: Fix where condition on delete when used from the cli.

**New feature:** Add query arguments support in to_dict:

python
temperature = Schema.get("temperature")
records = temperature.select().where("(= value {})").to_dict(12)


**New feature:** Type `timestamptz` is now accepted for SQLite.

**New feature:** Create new cursor for each execute, it allows for
example to iterate on select and update the db record by record

**New feature:** Add `Update` class and basic tests, this is mainly
useful when updating by id when the full natural key is not known (or
too long)

**Fix:** `limit` and `offset` values where lost on Select.clone

**Fix** Auto-convert pandas columns to string for non-basic dtypes

**Fix:** Ensure schema loading is correct

**New feature:** Add support for custom primary key

**New:** Add db introspection:
- Discovery of columns and types
- Discovery of primary keys and unique indexes

**Breaking change:** `Select.to_dict` now returns an iterable

**New feature:** `Select.to_pandas` supports a `chunked` parameter: if
set to a non-zero value the method will return an iterable yielding
dataframes instead returning of a unique (possibly large) dataframe

**New feature:** Add `table.drop()`

**New feature:** Check for inconsistencies on hill-defined tables

**Breaking change:** Foreign keys are know defined with an `ON DELETE
CASCADE` pragma if the supporting column is required

**New feature:** Add support for UUID type

**New feature:** Support for concat `||` operator

**New feature:** Add support for default values on table columns

**Breaking change:** `load_schema()` has been replaced by Schema.load
(and Schema.from_toml).

**New feature:** Transaction can now be used without a context
manager, this provide more flexibility in multi-threaded app.

**New feature:** CockroachDB support

**New feature:** Add new column on existing tables on schema
creation. Before any existing table was kept as-is.

**New feature:** Auto validation of rows when a condition is given to
an upsert

**New feature:** New method `to_pandas` on Select.

**New feature:** Add support for one-to-many through table aliases

**New feature:** Upsert now returns the id of the rows created or
updated