operator/

statement.rs

// Copyright 2023 Greptime Team
//
// Licensed 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.

mod admin;
mod copy_database;
mod copy_query_to;
mod copy_table_from;
mod copy_table_to;
mod cursor;
mod ddl;
mod describe;
mod dml;
mod kill;
mod set;
mod show;
mod tql;

use std::collections::HashMap;
use std::pin::Pin;
use std::sync::Arc;
use std::time::Duration;

use async_stream::stream;
use catalog::kvbackend::KvBackendCatalogManager;
use catalog::process_manager::ProcessManagerRef;
use catalog::CatalogManagerRef;
use client::{OutputData, RecordBatches};
use common_error::ext::BoxedError;
use common_meta::cache::TableRouteCacheRef;
use common_meta::cache_invalidator::CacheInvalidatorRef;
use common_meta::ddl::ProcedureExecutorRef;
use common_meta::key::flow::{FlowMetadataManager, FlowMetadataManagerRef};
use common_meta::key::schema_name::SchemaNameKey;
use common_meta::key::view_info::{ViewInfoManager, ViewInfoManagerRef};
use common_meta::key::{TableMetadataManager, TableMetadataManagerRef};
use common_meta::kv_backend::KvBackendRef;
use common_query::Output;
use common_recordbatch::error::StreamTimeoutSnafu;
use common_recordbatch::RecordBatchStreamWrapper;
use common_telemetry::tracing;
use common_time::range::TimestampRange;
use common_time::Timestamp;
use datafusion_expr::LogicalPlan;
use futures::stream::{Stream, StreamExt};
use partition::manager::{PartitionRuleManager, PartitionRuleManagerRef};
use query::parser::QueryStatement;
use query::QueryEngineRef;
use session::context::{Channel, QueryContextRef};
use session::table_name::table_idents_to_full_name;
use set::{set_query_timeout, set_read_preference};
use snafu::{ensure, OptionExt, ResultExt};
use sql::statements::copy::{
    CopyDatabase, CopyDatabaseArgument, CopyQueryToArgument, CopyTable, CopyTableArgument,
};
use sql::statements::set_variables::SetVariables;
use sql::statements::show::ShowCreateTableVariant;
use sql::statements::statement::Statement;
use sql::statements::OptionMap;
use sql::util::format_raw_object_name;
use sqlparser::ast::ObjectName;
use table::requests::{CopyDatabaseRequest, CopyDirection, CopyQueryToRequest, CopyTableRequest};
use table::table_name::TableName;
use table::table_reference::TableReference;
use table::TableRef;

use self::set::{
    set_bytea_output, set_datestyle, set_search_path, set_timezone, validate_client_encoding,
};
use crate::error::{
    self, CatalogSnafu, ExecLogicalPlanSnafu, ExternalSnafu, InvalidSqlSnafu, NotSupportedSnafu,
    PlanStatementSnafu, Result, SchemaNotFoundSnafu, StatementTimeoutSnafu,
    TableMetadataManagerSnafu, TableNotFoundSnafu, UpgradeCatalogManagerRefSnafu,
};
use crate::insert::InserterRef;
use crate::statement::copy_database::{COPY_DATABASE_TIME_END_KEY, COPY_DATABASE_TIME_START_KEY};

#[derive(Clone)]
pub struct StatementExecutor {
    catalog_manager: CatalogManagerRef,
    query_engine: QueryEngineRef,
    procedure_executor: ProcedureExecutorRef,
    table_metadata_manager: TableMetadataManagerRef,
    flow_metadata_manager: FlowMetadataManagerRef,
    view_info_manager: ViewInfoManagerRef,
    partition_manager: PartitionRuleManagerRef,
    cache_invalidator: CacheInvalidatorRef,
    inserter: InserterRef,
    process_manager: Option<ProcessManagerRef>,
}

pub type StatementExecutorRef = Arc<StatementExecutor>;

impl StatementExecutor {
    #[allow(clippy::too_many_arguments)]
    pub fn new(
        catalog_manager: CatalogManagerRef,
        query_engine: QueryEngineRef,
        procedure_executor: ProcedureExecutorRef,
        kv_backend: KvBackendRef,
        cache_invalidator: CacheInvalidatorRef,
        inserter: InserterRef,
        table_route_cache: TableRouteCacheRef,
        process_manager: Option<ProcessManagerRef>,
    ) -> Self {
        Self {
            catalog_manager,
            query_engine,
            procedure_executor,
            table_metadata_manager: Arc::new(TableMetadataManager::new(kv_backend.clone())),
            flow_metadata_manager: Arc::new(FlowMetadataManager::new(kv_backend.clone())),
            view_info_manager: Arc::new(ViewInfoManager::new(kv_backend.clone())),
            partition_manager: Arc::new(PartitionRuleManager::new(kv_backend, table_route_cache)),
            cache_invalidator,
            inserter,
            process_manager,
        }
    }

    #[cfg(feature = "testing")]
    pub async fn execute_stmt(
        &self,
        stmt: QueryStatement,
        query_ctx: QueryContextRef,
    ) -> Result<Output> {
        match stmt {
            QueryStatement::Sql(stmt) => self.execute_sql(stmt, query_ctx).await,
            QueryStatement::Promql(_) => self.plan_exec(stmt, query_ctx).await,
        }
    }

    #[tracing::instrument(skip_all)]
    pub async fn execute_sql(&self, stmt: Statement, query_ctx: QueryContextRef) -> Result<Output> {
        match stmt {
            Statement::Query(_) | Statement::Explain(_) | Statement::Delete(_) => {
                self.plan_exec(QueryStatement::Sql(stmt), query_ctx).await
            }

            Statement::DeclareCursor(declare_cursor) => {
                self.declare_cursor(declare_cursor, query_ctx).await
            }
            Statement::FetchCursor(fetch_cursor) => {
                self.fetch_cursor(fetch_cursor, query_ctx).await
            }
            Statement::CloseCursor(close_cursor) => {
                self.close_cursor(close_cursor, query_ctx).await
            }

            Statement::Insert(insert) => self.insert(insert, query_ctx).await,

            Statement::Tql(tql) => self.execute_tql(tql, query_ctx).await,

            Statement::DescribeTable(stmt) => self.describe_table(stmt, query_ctx).await,

            Statement::ShowDatabases(stmt) => self.show_databases(stmt, query_ctx).await,

            Statement::ShowTables(stmt) => self.show_tables(stmt, query_ctx).await,

            Statement::ShowTableStatus(stmt) => self.show_table_status(stmt, query_ctx).await,

            Statement::ShowCollation(kind) => self.show_collation(kind, query_ctx).await,

            Statement::ShowCharset(kind) => self.show_charset(kind, query_ctx).await,

            Statement::ShowViews(stmt) => self.show_views(stmt, query_ctx).await,

            Statement::ShowFlows(stmt) => self.show_flows(stmt, query_ctx).await,

            #[cfg(feature = "enterprise")]
            Statement::ShowTriggers(stmt) => self.show_triggers(stmt, query_ctx).await,

            Statement::Copy(sql::statements::copy::Copy::CopyQueryTo(stmt)) => {
                let query_output = self
                    .plan_exec(QueryStatement::Sql(*stmt.query), query_ctx)
                    .await?;
                let req = to_copy_query_request(stmt.arg)?;

                self.copy_query_to(req, query_output)
                    .await
                    .map(Output::new_with_affected_rows)
            }

            Statement::Copy(sql::statements::copy::Copy::CopyTable(stmt)) => {
                let req = to_copy_table_request(stmt, query_ctx.clone())?;
                match req.direction {
                    CopyDirection::Export => self
                        .copy_table_to(req, query_ctx)
                        .await
                        .map(Output::new_with_affected_rows),
                    CopyDirection::Import => self.copy_table_from(req, query_ctx).await,
                }
            }

            Statement::Copy(sql::statements::copy::Copy::CopyDatabase(copy_database)) => {
                match copy_database {
                    CopyDatabase::To(arg) => {
                        self.copy_database_to(
                            to_copy_database_request(arg, &query_ctx)?,
                            query_ctx.clone(),
                        )
                        .await
                    }
                    CopyDatabase::From(arg) => {
                        self.copy_database_from(
                            to_copy_database_request(arg, &query_ctx)?,
                            query_ctx,
                        )
                        .await
                    }
                }
            }

            Statement::CreateTable(stmt) => {
                let _ = self.create_table(stmt, query_ctx).await?;
                Ok(Output::new_with_affected_rows(0))
            }
            Statement::CreateTableLike(stmt) => {
                let _ = self.create_table_like(stmt, query_ctx).await?;
                Ok(Output::new_with_affected_rows(0))
            }
            Statement::CreateExternalTable(stmt) => {
                let _ = self.create_external_table(stmt, query_ctx).await?;
                Ok(Output::new_with_affected_rows(0))
            }
            Statement::CreateFlow(stmt) => self.create_flow(stmt, query_ctx).await,
            #[cfg(feature = "enterprise")]
            Statement::CreateTrigger(stmt) => self.create_trigger(stmt, query_ctx).await,
            Statement::DropFlow(stmt) => {
                self.drop_flow(
                    query_ctx.current_catalog().to_string(),
                    format_raw_object_name(stmt.flow_name()),
                    stmt.drop_if_exists(),
                    query_ctx,
                )
                .await
            }
            #[cfg(feature = "enterprise")]
            Statement::DropTrigger(stmt) => {
                self.drop_trigger(
                    query_ctx.current_catalog().to_string(),
                    format_raw_object_name(stmt.trigger_name()),
                    stmt.drop_if_exists(),
                    query_ctx,
                )
                .await
            }
            Statement::CreateView(stmt) => {
                let _ = self.create_view(stmt, query_ctx).await?;
                Ok(Output::new_with_affected_rows(0))
            }
            Statement::DropView(stmt) => {
                let (catalog_name, schema_name, view_name) =
                    table_idents_to_full_name(&stmt.view_name, &query_ctx)
                        .map_err(BoxedError::new)
                        .context(ExternalSnafu)?;

                self.drop_view(
                    catalog_name,
                    schema_name,
                    view_name,
                    stmt.drop_if_exists,
                    query_ctx,
                )
                .await
            }
            Statement::AlterTable(alter_table) => self.alter_table(alter_table, query_ctx).await,

            Statement::AlterDatabase(alter_database) => {
                self.alter_database(alter_database, query_ctx).await
            }

            Statement::DropTable(stmt) => {
                let mut table_names = Vec::with_capacity(stmt.table_names().len());
                for table_name_stmt in stmt.table_names() {
                    let (catalog, schema, table) =
                        table_idents_to_full_name(table_name_stmt, &query_ctx)
                            .map_err(BoxedError::new)
                            .context(ExternalSnafu)?;
                    table_names.push(TableName::new(catalog, schema, table));
                }
                self.drop_tables(&table_names[..], stmt.drop_if_exists(), query_ctx.clone())
                    .await
            }
            Statement::DropDatabase(stmt) => {
                self.drop_database(
                    query_ctx.current_catalog().to_string(),
                    format_raw_object_name(stmt.name()),
                    stmt.drop_if_exists(),
                    query_ctx,
                )
                .await
            }
            Statement::TruncateTable(stmt) => {
                let (catalog, schema, table) =
                    table_idents_to_full_name(stmt.table_name(), &query_ctx)
                        .map_err(BoxedError::new)
                        .context(ExternalSnafu)?;
                let table_name = TableName::new(catalog, schema, table);
                self.truncate_table(table_name, query_ctx).await
            }
            Statement::CreateDatabase(stmt) => {
                self.create_database(
                    &format_raw_object_name(&stmt.name),
                    stmt.if_not_exists,
                    stmt.options.into_map(),
                    query_ctx,
                )
                .await
            }
            Statement::ShowCreateDatabase(show) => {
                let (catalog, database) =
                    idents_to_full_database_name(&show.database_name, &query_ctx)
                        .map_err(BoxedError::new)
                        .context(ExternalSnafu)?;
                let table_metadata_manager = self
                    .catalog_manager
                    .as_any()
                    .downcast_ref::<KvBackendCatalogManager>()
                    .map(|manager| manager.table_metadata_manager_ref().clone())
                    .context(UpgradeCatalogManagerRefSnafu)?;
                let opts: HashMap<String, String> = table_metadata_manager
                    .schema_manager()
                    .get(SchemaNameKey::new(&catalog, &database))
                    .await
                    .context(TableMetadataManagerSnafu)?
                    .context(SchemaNotFoundSnafu {
                        schema_info: &database,
                    })?
                    .into_inner()
                    .into();

                self.show_create_database(&database, opts.into()).await
            }
            Statement::ShowCreateTable(show) => {
                let (catalog, schema, table) =
                    table_idents_to_full_name(&show.table_name, &query_ctx)
                        .map_err(BoxedError::new)
                        .context(ExternalSnafu)?;

                let table_ref = self
                    .catalog_manager
                    .table(&catalog, &schema, &table, Some(&query_ctx))
                    .await
                    .context(CatalogSnafu)?
                    .context(TableNotFoundSnafu { table_name: &table })?;
                let table_name = TableName::new(catalog, schema, table);

                match show.variant {
                    ShowCreateTableVariant::Original => {
                        self.show_create_table(table_name, table_ref, query_ctx)
                            .await
                    }
                    ShowCreateTableVariant::PostgresForeignTable => {
                        self.show_create_table_for_pg(table_name, table_ref, query_ctx)
                            .await
                    }
                }
            }
            Statement::ShowCreateFlow(show) => self.show_create_flow(show, query_ctx).await,
            Statement::ShowCreateView(show) => self.show_create_view(show, query_ctx).await,
            Statement::SetVariables(set_var) => self.set_variables(set_var, query_ctx),
            Statement::ShowVariables(show_variable) => self.show_variable(show_variable, query_ctx),
            Statement::ShowColumns(show_columns) => {
                self.show_columns(show_columns, query_ctx).await
            }
            Statement::ShowIndex(show_index) => self.show_index(show_index, query_ctx).await,
            Statement::ShowRegion(show_region) => self.show_region(show_region, query_ctx).await,
            Statement::ShowStatus(_) => self.show_status(query_ctx).await,
            Statement::ShowSearchPath(_) => self.show_search_path(query_ctx).await,
            Statement::Use(db) => self.use_database(db, query_ctx).await,
            Statement::Admin(admin) => self.execute_admin_command(admin, query_ctx).await,
            Statement::Kill(kill) => self.execute_kill(query_ctx, kill).await,
            Statement::ShowProcesslist(show) => self.show_processlist(show, query_ctx).await,
        }
    }

    pub async fn use_database(&self, db: String, query_ctx: QueryContextRef) -> Result<Output> {
        let catalog = query_ctx.current_catalog();
        ensure!(
            self.catalog_manager
                .schema_exists(catalog, db.as_ref(), Some(&query_ctx))
                .await
                .context(CatalogSnafu)?,
            SchemaNotFoundSnafu { schema_info: &db }
        );

        query_ctx.set_current_schema(&db);

        Ok(Output::new_with_record_batches(RecordBatches::empty()))
    }

    fn set_variables(&self, set_var: SetVariables, query_ctx: QueryContextRef) -> Result<Output> {
        let var_name = set_var.variable.to_string().to_uppercase();

        match var_name.as_str() {
            "READ_PREFERENCE" => set_read_preference(set_var.value, query_ctx)?,

            "@@TIME_ZONE" | "@@SESSION.TIME_ZONE" | "TIMEZONE" | "TIME_ZONE" => {
                set_timezone(set_var.value, query_ctx)?
            }

            "BYTEA_OUTPUT" => set_bytea_output(set_var.value, query_ctx)?,

            // Same as "bytea_output", we just ignore it here.
            // Not harmful since it only relates to how date is viewed in client app's output.
            // The tracked issue is https://github.com/GreptimeTeam/greptimedb/issues/3442.
            "DATESTYLE" => set_datestyle(set_var.value, query_ctx)?,

            "CLIENT_ENCODING" => validate_client_encoding(set_var)?,
            "@@SESSION.MAX_EXECUTION_TIME" | "MAX_EXECUTION_TIME" => match query_ctx.channel() {
                Channel::Mysql => set_query_timeout(set_var.value, query_ctx)?,
                Channel::Postgres => {
                    query_ctx.set_warning(format!("Unsupported set variable {}", var_name))
                }
                _ => {
                    return NotSupportedSnafu {
                        feat: format!("Unsupported set variable {}", var_name),
                    }
                    .fail()
                }
            },
            "STATEMENT_TIMEOUT" => {
                if query_ctx.channel() == Channel::Postgres {
                    set_query_timeout(set_var.value, query_ctx)?
                } else {
                    return NotSupportedSnafu {
                        feat: format!("Unsupported set variable {}", var_name),
                    }
                    .fail();
                }
            }
            "SEARCH_PATH" => {
                if query_ctx.channel() == Channel::Postgres {
                    set_search_path(set_var.value, query_ctx)?
                } else {
                    return NotSupportedSnafu {
                        feat: format!("Unsupported set variable {}", var_name),
                    }
                    .fail();
                }
            }
            _ => {
                // for postgres, we give unknown SET statements a warning with
                //  success, this is prevent the SET call becoming a blocker
                //  of connection establishment
                //
                if query_ctx.channel() == Channel::Postgres {
                    query_ctx.set_warning(format!("Unsupported set variable {}", var_name));
                } else if query_ctx.channel() == Channel::Mysql && var_name.starts_with("@@") {
                    // Just ignore `SET @@` commands for MySQL
                    query_ctx.set_warning(format!("Unsupported set variable {}", var_name));
                } else {
                    return NotSupportedSnafu {
                        feat: format!("Unsupported set variable {}", var_name),
                    }
                    .fail();
                }
            }
        }
        Ok(Output::new_with_affected_rows(0))
    }

    #[tracing::instrument(skip_all)]
    pub async fn plan(
        &self,
        stmt: &QueryStatement,
        query_ctx: QueryContextRef,
    ) -> Result<LogicalPlan> {
        self.query_engine
            .planner()
            .plan(stmt, query_ctx)
            .await
            .context(PlanStatementSnafu)
    }

    /// Execute [`LogicalPlan`] directly.
    #[tracing::instrument(skip_all)]
    pub async fn exec_plan(&self, plan: LogicalPlan, query_ctx: QueryContextRef) -> Result<Output> {
        self.query_engine
            .execute(plan, query_ctx)
            .await
            .context(ExecLogicalPlanSnafu)
    }

    pub fn optimize_logical_plan(&self, plan: LogicalPlan) -> Result<LogicalPlan> {
        self.query_engine
            .planner()
            .optimize(plan)
            .context(PlanStatementSnafu)
    }

    #[tracing::instrument(skip_all)]
    async fn plan_exec(&self, stmt: QueryStatement, query_ctx: QueryContextRef) -> Result<Output> {
        let timeout = derive_timeout(&stmt, &query_ctx);
        match timeout {
            Some(timeout) => {
                let start = tokio::time::Instant::now();
                let output = tokio::time::timeout(timeout, self.plan_exec_inner(stmt, query_ctx))
                    .await
                    .context(StatementTimeoutSnafu)?;
                // compute remaining timeout
                let remaining_timeout = timeout.checked_sub(start.elapsed()).unwrap_or_default();
                Ok(attach_timeout(output?, remaining_timeout))
            }
            None => self.plan_exec_inner(stmt, query_ctx).await,
        }
    }

    async fn get_table(&self, table_ref: &TableReference<'_>) -> Result<TableRef> {
        let TableReference {
            catalog,
            schema,
            table,
        } = table_ref;
        self.catalog_manager
            .table(catalog, schema, table, None)
            .await
            .context(CatalogSnafu)?
            .with_context(|| TableNotFoundSnafu {
                table_name: table_ref.to_string(),
            })
    }

    async fn plan_exec_inner(
        &self,
        stmt: QueryStatement,
        query_ctx: QueryContextRef,
    ) -> Result<Output> {
        let plan = self.plan(&stmt, query_ctx.clone()).await?;
        self.exec_plan(plan, query_ctx).await
    }
}

fn attach_timeout(output: Output, mut timeout: Duration) -> Output {
    match output.data {
        OutputData::AffectedRows(_) | OutputData::RecordBatches(_) => output,
        OutputData::Stream(mut stream) => {
            let schema = stream.schema();
            let s = Box::pin(stream! {
                let start = tokio::time::Instant::now();
                while let Some(item) = tokio::time::timeout(timeout, stream.next()).await.context(StreamTimeoutSnafu)? {
                    yield item;
                    timeout = timeout.checked_sub(tokio::time::Instant::now() - start).unwrap_or(Duration::ZERO);
                }
            }) as Pin<Box<dyn Stream<Item = _> + Send>>;
            let stream = RecordBatchStreamWrapper {
                schema,
                stream: s,
                output_ordering: None,
                metrics: Default::default(),
            };
            Output::new(OutputData::Stream(Box::pin(stream)), output.meta)
        }
    }
}

/// If the relevant variables are set, the timeout is enforced for all PostgreSQL statements.
/// For MySQL, it applies only to read-only statements.
fn derive_timeout(stmt: &QueryStatement, query_ctx: &QueryContextRef) -> Option<Duration> {
    let query_timeout = query_ctx.query_timeout()?;
    match (query_ctx.channel(), stmt) {
        (Channel::Mysql, QueryStatement::Sql(Statement::Query(_)))
        | (Channel::Postgres, QueryStatement::Sql(_)) => Some(query_timeout),
        (_, _) => None,
    }
}

fn to_copy_query_request(stmt: CopyQueryToArgument) -> Result<CopyQueryToRequest> {
    let CopyQueryToArgument {
        with,
        connection,
        location,
    } = stmt;

    Ok(CopyQueryToRequest {
        location,
        with: with.into_map(),
        connection: connection.into_map(),
    })
}

fn to_copy_table_request(stmt: CopyTable, query_ctx: QueryContextRef) -> Result<CopyTableRequest> {
    let direction = match stmt {
        CopyTable::To(_) => CopyDirection::Export,
        CopyTable::From(_) => CopyDirection::Import,
    };

    let CopyTableArgument {
        location,
        connection,
        with,
        table_name,
        limit,
        ..
    } = match stmt {
        CopyTable::To(arg) => arg,
        CopyTable::From(arg) => arg,
    };
    let (catalog_name, schema_name, table_name) =
        table_idents_to_full_name(&table_name, &query_ctx)
            .map_err(BoxedError::new)
            .context(ExternalSnafu)?;

    let timestamp_range = timestamp_range_from_option_map(&with, &query_ctx)?;

    let pattern = with
        .get(common_datasource::file_format::FILE_PATTERN)
        .cloned();

    Ok(CopyTableRequest {
        catalog_name,
        schema_name,
        table_name,
        location,
        with: with.into_map(),
        connection: connection.into_map(),
        pattern,
        direction,
        timestamp_range,
        limit,
    })
}

/// Converts [CopyDatabaseArgument] to [CopyDatabaseRequest].
/// This function extracts the necessary info including catalog/database name, time range, etc.
fn to_copy_database_request(
    arg: CopyDatabaseArgument,
    query_ctx: &QueryContextRef,
) -> Result<CopyDatabaseRequest> {
    let (catalog_name, database_name) = idents_to_full_database_name(&arg.database_name, query_ctx)
        .map_err(BoxedError::new)
        .context(ExternalSnafu)?;
    let time_range = timestamp_range_from_option_map(&arg.with, query_ctx)?;

    Ok(CopyDatabaseRequest {
        catalog_name,
        schema_name: database_name,
        location: arg.location,
        with: arg.with.into_map(),
        connection: arg.connection.into_map(),
        time_range,
    })
}

/// Extracts timestamp range from OptionMap with keys `start_time` and `end_time`.
/// The timestamp ranges should be a valid timestamp string as defined in [Timestamp::from_str].
/// The timezone used for conversion will respect that inside `query_ctx`.
fn timestamp_range_from_option_map(
    options: &OptionMap,
    query_ctx: &QueryContextRef,
) -> Result<Option<TimestampRange>> {
    let start_timestamp = extract_timestamp(options, COPY_DATABASE_TIME_START_KEY, query_ctx)?;
    let end_timestamp = extract_timestamp(options, COPY_DATABASE_TIME_END_KEY, query_ctx)?;
    let time_range = match (start_timestamp, end_timestamp) {
        (Some(start), Some(end)) => Some(TimestampRange::new(start, end).with_context(|| {
            error::InvalidTimestampRangeSnafu {
                start: start.to_iso8601_string(),
                end: end.to_iso8601_string(),
            }
        })?),
        (Some(start), None) => Some(TimestampRange::from_start(start)),
        (None, Some(end)) => Some(TimestampRange::until_end(end, false)), // exclusive end
        (None, None) => None,
    };
    Ok(time_range)
}

/// Extracts timestamp from a [HashMap<String, String>] with given key.
fn extract_timestamp(
    map: &OptionMap,
    key: &str,
    query_ctx: &QueryContextRef,
) -> Result<Option<Timestamp>> {
    map.get(key)
        .map(|v| {
            Timestamp::from_str(v, Some(&query_ctx.timezone()))
                .map_err(|_| error::InvalidCopyParameterSnafu { key, value: v }.build())
        })
        .transpose()
}

fn idents_to_full_database_name(
    obj_name: &ObjectName,
    query_ctx: &QueryContextRef,
) -> Result<(String, String)> {
    match &obj_name.0[..] {
        [database] => Ok((
            query_ctx.current_catalog().to_owned(),
            database.value.clone(),
        )),
        [catalog, database] => Ok((catalog.value.clone(), database.value.clone())),
        _ => InvalidSqlSnafu {
            err_msg: format!(
                "expect database name to be <catalog>.<database>, <database>, found: {obj_name}",
            ),
        }
        .fail(),
    }
}

#[cfg(test)]
mod tests {
    use std::assert_matches::assert_matches;
    use std::collections::HashMap;

    use common_time::range::TimestampRange;
    use common_time::{Timestamp, Timezone};
    use session::context::QueryContextBuilder;
    use sql::statements::OptionMap;

    use crate::error;
    use crate::statement::copy_database::{
        COPY_DATABASE_TIME_END_KEY, COPY_DATABASE_TIME_START_KEY,
    };
    use crate::statement::timestamp_range_from_option_map;

    fn check_timestamp_range((start, end): (&str, &str)) -> error::Result<Option<TimestampRange>> {
        let query_ctx = QueryContextBuilder::default()
            .timezone(Timezone::from_tz_string("Asia/Shanghai").unwrap())
            .build()
            .into();
        let map = OptionMap::from(
            [
                (COPY_DATABASE_TIME_START_KEY.to_string(), start.to_string()),
                (COPY_DATABASE_TIME_END_KEY.to_string(), end.to_string()),
            ]
            .into_iter()
            .collect::<HashMap<_, _>>(),
        );
        timestamp_range_from_option_map(&map, &query_ctx)
    }

    #[test]
    fn test_timestamp_range_from_option_map() {
        assert_eq!(
            Some(
                TimestampRange::new(
                    Timestamp::new_second(1649635200),
                    Timestamp::new_second(1649664000),
                )
                .unwrap(),
            ),
            check_timestamp_range(("2022-04-11 08:00:00", "2022-04-11 16:00:00"),).unwrap()
        );

        assert_matches!(
            check_timestamp_range(("2022-04-11 08:00:00", "2022-04-11 07:00:00")).unwrap_err(),
            error::Error::InvalidTimestampRange { .. }
        );
    }
}