parqlite 0.1.4

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parqlite

Local-first Python storage library backed by Iceberg metadata, Parquet data files, and DuckDB SQL queries.

parqlite is useful when you want a small local analytical database with:

• Iceberg table metadata and snapshots
• Parquet data files
• DuckDB SQL reads
• explicit append and full-table overwrite writes
• snapshot time travel, tags, rollback, and maintenance helpers

v1 intentionally stays small. It does not implement write, upsert, merge, delete, or schema evolution. keys and version_by are stored as reserved table metadata for future deduplication features, but they do not enforce uniqueness in v1.

Install

This repo uses uv:

UV_CACHE_DIR=/tmp/uv-cache uv sync

Run tests:

UV_CACHE_DIR=/tmp/uv-cache uv run pytest

Quick Start

import pandas as pd

from parqlite import connect, month, t

db = connect("./data")

db.create_table(
    "factor_values",
    schema={
        "factor": t.string,
        "date": t.date,
        "instrument_id": t.string,
        "value": t.double,
        "updated_at": t.timestamp,
    },
    partition_by=[month("date")],
    keys=["factor", "date", "instrument_id"],
    version_by="updated_at",
)

db.append(
    "factor_values",
    pd.DataFrame(
        {
            "factor": ["quality", "quality"],
            "date": pd.to_datetime(["2024-01-31", "2024-02-29"]).date,
            "instrument_id": ["000001", "000002"],
            "value": [1.2, 0.8],
            "updated_at": pd.to_datetime(
                ["2024-03-01 09:00:00", "2024-03-01 09:01:00"]
            ),
        }
    ),
)

rows = db.sql(
    """
    select factor, instrument_id, value
    from factor_values
    order by instrument_id
    """
).fetchall()

Connect

connect(path) opens or creates a local parqlite directory.

from parqlite import connect

db = connect("./data")

The directory contains a local SQL catalog database and an Iceberg warehouse:

data/
  catalog.db
  warehouse/

Close the DuckDB connection when you are done:

db.close()

Or use DB as a context manager:

with connect("./data") as db:
    tables = db.tables()

Schemas

Use parqlite.types helpers for schemas:

from parqlite import t

schema = {
    "id": t.long,
    "active": t.boolean,
    "price": t.decimal(18, 4),
    "payload": t.binary,
    "fixed_hash": t.fixed(16),
    "created_at": t.timestamp,
}

Supported helpers:

• t.boolean
• t.int
• t.long
• t.float
• t.double
• t.date
• t.time
• t.timestamp
• t.timestamptz
• t.string
• t.uuid
• t.binary
• t.decimal(precision, scale)
• t.fixed(length)

Raw Iceberg type strings are also accepted:

db.create_table("items", {"id": "long", "name": "string"})

Input data columns must match the table schema exactly, including column order.

Create Tables

from parqlite import bucket, day, hour, identity, month, truncate, year

db.create_table(
    "events",
    schema={
        "event_id": "long",
        "event_date": "date",
        "customer_id": "string",
        "event_type": "string",
    },
    partition_by=[
        month("event_date"),
        bucket("customer_id", 16),
        truncate("event_type", 8),
    ],
    keys=["event_id"],
    properties={
        "write.metadata.delete-after-commit.enabled": True,
        "write.metadata.previous-versions-max": 5,
    },
)

Pass if_not_exists=True to make creation a no-op when the table already exists. Existing table schema, partitioning, and properties are not modified.

Partition helpers:

• identity("column"), or pass "column" directly in partition_by
• year("date_column")
• month("date_column")
• day("date_column")
• hour("timestamp_column")
• bucket("column", num_buckets)
• truncate("column", width)

properties accepts Iceberg table properties. Values may be strings, integers, or booleans. Booleans and integers are stored as strings in Iceberg metadata. The examples above are not the full Iceberg property list; they are common maintenance-related properties. See the Apache Iceberg configuration docs for the complete current table property reference: https://iceberg.apache.org/docs/latest/configuration/#table-properties

parqlite exports IcebergTablePropertyKey as a Literal[...] type alias for the official static Iceberg table property keys:

from parqlite import IcebergTablePropertyKey, TablePropertyValue

props: dict[IcebergTablePropertyKey, TablePropertyValue] = {
    "history.expire.max-snapshot-age-ms": 7 * 24 * 60 * 60 * 1000,
    "history.expire.min-snapshots-to-keep": 2,
}

The create_table(..., properties=...) and set_table_properties(...) APIs still accept general string keys. That is intentional because Iceberg also has column-scoped keys such as write.metadata.metrics.column.<column_name> and parqlite allows custom informational keys such as custom.owner.

parqlite.keys and parqlite.version_by are reserved. Set them through keys= and version_by=, not through properties=.

Write Data

append(table, data) appends records and creates a new Iceberg snapshot.

import pandas as pd
import pyarrow as pa

db.append("items", pd.DataFrame({"id": [1, 2], "name": ["a", "b"]}))
db.append("items", pa.table({"id": [3], "name": ["c"]}))
db.append("items", "./more_items.parquet")
db.append("items", "./more_items.csv")
db.append("items", "./more_items.jsonl")

Supported file inputs:

• .parquet
• .csv
• .json
• .jsonl
• .ndjson

overwrite(table, data) replaces the visible table contents with data and creates a new snapshot:

db.overwrite("items", pd.DataFrame({"id": [10], "name": ["replacement"]}))

Query With SQL

sql(query) returns a DuckDB relation:

relation = db.sql("select id, name from items order by id")

rows = relation.fetchall()
df = relation.df()
one = db.sql("select count(*) from items").fetchone()[0]

parqlite refreshes DuckDB views against the latest Iceberg metadata.json on each SQL call.

Table Introspection

tables = db.tables()
exists = db.table_exists("items")
schema = db.schema("items")
properties = db.table_properties("items")

Drop a table:

db.drop_table("items")
db.drop_table("items", if_exists=True)

Namespaces

The default namespace always exists. Additional namespaces let you use table names such as binance.klines.

db.create_namespace("binance")
db.create_namespace("binance", if_not_exists=True)

namespaces = db.list_namespaces()

db.drop_namespace("binance")
db.drop_namespace("binance", if_exists=True)

drop_namespace only removes empty non-default namespaces.

CLI

The CLI keeps the command shape parqlite <command> <path> ...:

parqlite ui ./data
parqlite tables ./data
parqlite schema ./data items
parqlite sql ./data
parqlite sql ./data "select * from items order by id"

tables runs a DuckDB catalog query after preloading the current parqlite tables as views, then displays table names with DuckDB's native output.

schema runs DuckDB's native DESCRIBE command after preloading the current parqlite tables as views.

sql starts DuckDB CLI with the current parqlite tables preloaded as views. If you pass a query, DuckDB runs it and exits. Without a query, DuckDB opens an interactive shell.

Table Properties

Read, set, and remove Iceberg table properties:

props = db.table_properties("items")

updated = db.set_table_properties(
    "items",
    {
        "history.expire.max-snapshot-age-ms": 7 * 24 * 60 * 60 * 1000,
        "history.expire.min-snapshots-to-keep": 2,
        "write.metadata.delete-after-commit.enabled": True,
        "write.metadata.previous-versions-max": 3,
        "custom.owner": "research",
    },
)

updated = db.remove_table_properties("items", ["custom.owner"])

Use metadata retention properties to let PyIceberg delete old tracked metadata files after commits:

db.set_table_properties(
    "items",
    {
        "write.metadata.delete-after-commit.enabled": True,
        "write.metadata.previous-versions-max": 1,
    },
)

This only applies to metadata files tracked by the table metadata log. Untracked metadata files can still be removed by orphan cleanup.

Snapshots

Inspect snapshots:

current = db.current_snapshot("items")
snapshots = db.snapshots("items")
recent = db.snapshots("items", limit=5)

print(current.snapshot_id)
print(current.parent_id)
print(current.committed_at)
print(current.operation)

current_snapshot and snapshots return TableSnapshot objects with:

• snapshot_id
• parent_id
• committed_at
• operation
• manifest_list
• summary

Time Travel

Use snapshot selectors from the top-level package:

from parqlite import as_of, ref, snapshot_id

first = db.snapshots("items")[0]

rows_by_id = db.sql(
    "select * from items",
    at={"items": snapshot_id(first.snapshot_id)},
).fetchall()

rows_by_time = db.sql(
    "select * from items",
    at={"items": as_of(first.committed_at)},
).fetchall()

When a SQL query references more than one table, pass one selector per table that should be pinned:

db.sql(
    """
    select *
    from left_items l
    join right_items r on l.id = r.id
    """,
    at={
        "left_items": snapshot_id(left_snapshot_id),
        "right_items": snapshot_id(right_snapshot_id),
    },
)

Datetime selectors must be timezone-aware.

Tags And Rollback

Create a tag for a snapshot:

from parqlite import ref, snapshot_id

current = db.current_snapshot("items")
db.create_tag("items", "stable", at=snapshot_id(current.snapshot_id))

Read a tag:

stable_rows = db.sql(
    "select * from items",
    at={"items": ref("stable")},
).fetchall()

List refs:

for snapshot_ref in db.refs("items"):
    print(snapshot_ref.name, snapshot_ref.type, snapshot_ref.snapshot_id)

Delete a tag:

db.delete_tag("items", "stable")

Rollback the table to a previous snapshot or time:

db.rollback_to("items", snapshot_id(previous_snapshot_id))
db.rollback_to("items", as_of(previous_timestamp))

Rollback changes the current table snapshot and creates metadata changes through PyIceberg.

Snapshot Expiration

expire_snapshots removes old snapshots from table metadata using PyIceberg's native maintenance transaction.

Expire snapshots older than a cutoff:

from datetime import datetime, timezone

result = db.expire_snapshots(
    "items",
    older_than=datetime(2024, 1, 1, tzinfo=timezone.utc),
)

print(result.expired_snapshot_ids)
print(result.expired_snapshots_count)

Expire snapshots by ID:

result = db.expire_snapshots("items", snapshot_ids=[old_snapshot_id])

Protect the most recent current-branch ancestor snapshots while expiring older ones:

from datetime import timedelta

result = db.expire_snapshots(
    "items",
    older_than=timedelta(days=30),
    retain_last=2,
)

If both older_than and snapshot_ids are omitted, parqlite uses Iceberg table properties:

db.set_table_properties(
    "items",
    {
        "history.expire.max-snapshot-age-ms": 5 * 24 * 60 * 60 * 1000,
        "history.expire.min-snapshots-to-keep": 1,
    },
)

result = db.expire_snapshots("items")

Important details:

• retain_last only protects recent current-branch ancestor snapshots.
• Tags and branch heads are protected by Iceberg and are not expired.
• Snapshot expiration updates metadata only. It does not delete orphan files by itself.

Orphan File Cleanup

Use remove_orphan_files after snapshot expiration to preview and then delete files that are no longer reachable from current table metadata.

Always preview first:

preview = db.remove_orphan_files("items", dry_run=True)

for file in preview.files:
    print(file.path, file.size_bytes, file.modified_at)

Delete the same kind of candidates:

result = db.remove_orphan_files("items")

print(result.deleted_files_count)
print(result.deleted_bytes)
print(result.by_suffix)

remove_orphan_files returns RemoveOrphanFilesResult:

• files: candidate or deleted OrphanFile entries
• dry_run: whether files were only previewed
• deleted_files_count
• deleted_bytes
• by_suffix: count by file suffix, such as {".parquet": 4}

By default, orphan cleanup only considers files older than 3 days. This safety window avoids deleting files from recent or in-progress writes.

Use a custom cutoff:

from datetime import timedelta

preview = db.remove_orphan_files(
    "items",
    older_than=timedelta(days=7),
    dry_run=True,
)

Limit cleanup to a table subdirectory:

preview = db.remove_orphan_files(
    "items",
    location="metadata",
    dry_run=True,
)

location must be under the table root. parqlite currently supports local file-backed tables only for orphan cleanup.

There is no vacuum or optimize API. Use the Iceberg-native sequence instead:

db.expire_snapshots("items", older_than=timedelta(days=30), retain_last=2)
preview = db.remove_orphan_files("items", dry_run=True)
deleted = db.remove_orphan_files("items")

Result Types

ExpireSnapshotsResult:

result.expired_snapshot_ids
result.expired_snapshots_count

RemoveOrphanFilesResult:

result.files
result.dry_run
result.deleted_files_count
result.deleted_bytes
result.by_suffix

OrphanFile:

file.path
file.size_bytes
file.modified_at

Examples

Create a local ./crypto database directory, create the binance namespace, and import the included Binance BTCUSDT one-minute klines CSV files into binance.klines:

UV_CACHE_DIR=/tmp/uv-cache uv run python examples/import_binance_klines.py

Create a local ./cn_market database directory, recreate the factor table, and insert deterministic sample factor values:

UV_CACHE_DIR=/tmp/uv-cache uv run python examples/write_cn_market.py

Use PARQLITE_EXAMPLE_ROWS to run a smaller sample:

PARQLITE_EXAMPLE_ROWS=10000 UV_CACHE_DIR=/tmp/uv-cache uv run python examples/write_cn_market.py

Read the factor table and run sample analytical queries:

UV_CACHE_DIR=/tmp/uv-cache uv run python examples/read_cn_market.py

Inspect snapshots and read a tagged snapshot:

UV_CACHE_DIR=/tmp/uv-cache uv run python examples/read_version.py

Storage And SQL Notes

parqlite uses PyIceberg for local catalog management, table creation, appends, overwrites, drops, snapshots, table properties, and metadata commits. Table data is stored as Parquet files under the local warehouse.

SQL reads use DuckDB's Iceberg extension. The first SQL query for a database may need DuckDB to install the iceberg extension into DuckDB's default user extension directory. If that directory is not writable, or DuckDB cannot download or load the extension, parqlite raises a query backend error that includes DuckDB's original error.