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GraphQL service for arrow tables and parquet data sets. The schema is derived automatically.
Usage¶
% env PARQUET_PATH=... uvicorn graphique.service:app
Open http://localhost:8000/graphql to try out the API in GraphiQL.
There is a test fixture at ./tests/fixtures/zipcodes.parquet.
Configuration¶
Graphique uses Starlette’s config: in environment variables or a .env file.
Config variables are used as input to ParquetDataset.
- COLUMNS = None
- DEBUG = False
- DICTIONARIES = None
- INDEX = None
- MMAP = True
- PARQUET_PATH
Queries¶
A Table is the primary interface. It has fields for filtering, sorting, and grouping.
"""a column-oriented table"""
type Table {
"""number of rows"""
length: Long!
"""fields for each column"""
columns: Columns!
"""Return scalar values at index."""
row(index: Long! = 0): Row!
"""Return table slice."""
slice(offset: Long! = 0, length: Long): Table!
"""
Return tables grouped by columns, with stable ordering.
`length` is the maximum number of tables to return.
`count` filters and sorts tables based on the number of rows within each table.
"""
group(by: [String!]!, reverse: Boolean! = false, length: Long, count: LongReduce): [Table!]!
"""
Return table of first or last occurrences grouped by columns, with stable ordering.
"""
unique(by: [String!]!, reverse: Boolean! = false): Table!
"""Return table slice sorted by specified columns."""
sort(by: [String!]!, reverse: Boolean! = false, length: Long): Table!
"""Return table with minimum values per column."""
min(by: [String!]!): Table!
"""Return table with maximum values per column."""
max(by: [String!]!): Table!
"""
Return table with rows which match all (by default) queries.
`invert` optionally excludes matching rows.
`reduce` is the binary operator to combine filters; within a column all predicates must match.
"""
filter(query: Filters!, invert: Boolean! = false, reduce: Operator! = AND): Table!
Performance¶
Graphique relies on native pyarrow routines wherever possible. Otherwise it falls back to using NumPy, with zero-copy views. Graphique also has custom optimizations for grouping, dictionary-encoded arrays, and chunked arrays.
Specifying an INDEX of columns indicates the table is sorted, and enables a binary search interface.
"""
Return table with matching values for compound `index`.
Queries must be a prefix of the `index`.
Only one non-equal query is allowed, and applied last.
"""
search(...): Table!
Installation¶
% pip install graphique
Dependencies¶
- pyarrow >=2
- strawberry-graphql >=0.30
- pytz (optional timestamp support)
Changes¶
dev
ListColumnandStructColumntypesGroupstype withaggregatefieldgroupanduniqueoptimized- pyarrow >= 2 required