comphead commented on code in PR #11088: URL: https://github.com/apache/datafusion/pull/11088#discussion_r1663076358
########## datafusion-examples/examples/sql_frontend.rs: ########## @@ -0,0 +1,208 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +use arrow::datatypes::{DataType, Field, Schema, SchemaRef}; +use datafusion_common::config::ConfigOptions; +use datafusion_common::{plan_err, Result}; +use datafusion_expr::{ + AggregateUDF, Expr, LogicalPlan, ScalarUDF, TableProviderFilterPushDown, TableSource, + WindowUDF, +}; +use datafusion_optimizer::{ + Analyzer, AnalyzerRule, Optimizer, OptimizerConfig, OptimizerContext, OptimizerRule, +}; +use datafusion_sql::planner::{ContextProvider, SqlToRel}; +use datafusion_sql::sqlparser::dialect::PostgreSqlDialect; +use datafusion_sql::sqlparser::parser::Parser; +use datafusion_sql::TableReference; +use std::any::Any; +use std::sync::Arc; + +/// This example shows how to use DataFusion's SQL planner to parse SQL text and +/// build `LogicalPlan`s without executing them. +/// +/// For example, if you need a SQL planner and optimizer like Apache Calcite, +/// but do not want a Java runtime dependency for some reason, you could use +/// DataFusion as a SQL frontend. +/// +/// Normally, users interact with DataFusion via SessionContext. However, using +/// SessionContext requires depending on the full `datafusion` core crate. +/// +/// In this example, we demonstrate how to use the lower level APIs directly, +/// which only requires the `datafusion-sql` dependency. +pub fn main() -> Result<()> { + // First, we parse the SQL string. Note that we use the DataFusion + // Parser, which wraps the `sqlparser-rs` SQL parser and adds DataFusion + // specific syntax such as `CREATE EXTERNAL TABLE` + let dialect = PostgreSqlDialect {}; + let sql = "SELECT name FROM person WHERE age BETWEEN 21 AND 32"; + let statements = Parser::parse_sql(&dialect, sql)?; + + // Now, use DataFusion's SQL planner, called `SqlToRel` to create a + // `LogicalPlan` from the parsed statement + // + // To invoke SqlToRel we must provide it schema and function information + // via an object that implements the `ContextProvider` trait + // + // Projection: person.name + // Filter: person.age BETWEEN Int64(21) AND Int64(32) + // TableScan: person + let context_provider = MyContextProvider::default(); + let sql_to_rel = SqlToRel::new(&context_provider); + let logical_plan = sql_to_rel.sql_statement_to_plan(statements[0].clone())?; + println!( Review Comment: Filed https://github.com/apache/datafusion/issues/11230 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
