feat(server): Adding bulk fetch to get data at once (#20)

README.md

@@ -152,3 +152,8 @@ yarn cli query "SELECT 1;"
 # or installed global
 tentaclesql query "SELECT 1;"
 ```
+
+### Bulk fetch
+By default Tentacle sends one HTTP request for each table data, however you can change this and fetch all table data in one HTTP request. To enable this you need to pass following paramaters:
+- `BULK_FETCH=true`
+- `BULK_FETCH_URL=url`

src/executor/index.ts

@@ -69,6 +69,33 @@ async function fetchTableData (
   return res.json()
 }
 
+async function fetchTablesData (
+  tableDefinitions: Array<TableDefinition>,
+  headers: any,
+  queryAst: any,
+  method: 'POST' | 'GET' = 'POST'
+): Promise<any> {
+  if (process.env.BULK_FETCH_URL === undefined) {
+    return Error('Bulk fetch requested but bulk fetch url is not defined.')
+  }
+  const res = await fetch(
+    process.env.BULK_FETCH_URL, {
+      headers: headers,
+      method: method,
+      body: JSON.stringify({
+        query_ast: queryAst,
+        names: tableDefinitions.map((tableDefinition: TableDefinition) => tableDefinition.name)
+      })
+    }
+  )
+
+  if (!res.ok) {
+    return Promise.reject(new Error(`Error with the request. Status code: ${res.status}`))
+  }
+
+  return res.json()
+}
+
 async function populateTables (
   db: IDatabaseAdapter,
   usedTables: Array<string>,
@@ -81,46 +108,99 @@ async function populateTables (
   ) => usedTables.includes(tableDefinition.name))
 
   const promises = filteredTableDefinition.map(async (tableDefinition: TableDefinition) => {
-    const schemas = parseSchema(tableDefinition.fields).join(', ')
+    const data = await fetchTableData(tableDefinition, headers, queryAst)
+    syncData(tableDefinition, data, db)
+  })
+  return Promise.all(promises)
+}
 
-    if (!tableDefinition.autodiscover) {
-      db.createTable(tableDefinition, schemas)
-    }
+async function populateTablesInOneHTTPRequest (
+  db: IDatabaseAdapter,
+  usedTables: Array<string>,
+  headers: any,
+  schema: any,
+  queryAst: any
+) {
+  const filteredTableDefinition = schema.filter((
+    tableDefinition: TableDefinition
+  ) => usedTables.includes(tableDefinition.name))
+  const remoteData = await fetchTablesData(filteredTableDefinition, headers, queryAst)
+  filteredTableDefinition.forEach((tableDefinition: TableDefinition) => {
+    const targetTable = remoteData.find((tableData: any) => tableData.name === tableDefinition.name)
+    syncData(
+      tableDefinition,
+      targetTable.data,
+      db
+    )
+  })
+}
 
-    const data = await fetchTableData(tableDefinition, headers, queryAst)
+function syncData (
+  tableDefinition: TableDefinition,
+  data: any,
+  db: IDatabaseAdapter
+) {
+  const schemas = parseSchema(tableDefinition.fields).join(', ')
 
-    const resultKey = tableDefinition.resultKey
-    const dataPointer = resultKey ? data[resultKey] : data
-    const fixedData = dataPointer.map((field: any) => flattenObject(field, '_'))
+  if (!tableDefinition.autodiscover) {
+    db.createTable(tableDefinition, schemas)
+  }
 
-    if (fixedData.length === 0) return
+  const resultKey = tableDefinition.resultKey
+  const dataPointer = resultKey ? data[resultKey] : data
+  const fixedData = dataPointer.map((field: any) => flattenObject(field, '_'))
 
-    // No support for booleans :/
-    mutateDataframe(fixedData, (row, k) => {
-      if (typeof row[k] === 'boolean') row[k] = row[k] ? 'TRUE' : 'FALSE'
-    })
+  if (fixedData.length === 0) return
 
-    if (tableDefinition.autodiscover) {
-      const dynamicDefinition = {
-        name: tableDefinition.name,
-        fields: Object.keys(fixedData[0]).map((key) => ({ key: key }))
-      }
+  // No support for booleans :/
+  mutateDataframe(fixedData, (row, k) => {
+    if (typeof row[k] === 'boolean') row[k] = row[k] ? 'TRUE' : 'FALSE'
+  })
 
-      db.createTable(dynamicDefinition, schemas)
-      db.storeToDb(dynamicDefinition, fixedData)
-    } else {
-      db.storeToDb(tableDefinition, fixedData)
+  if (tableDefinition.autodiscover) {
+    const dynamicDefinition = {
+      name: tableDefinition.name,
+      fields: Object.keys(fixedData[0]).map((key) => ({ key: key }))
     }
-  })
 
-  return Promise.all(promises)
+    db.createTable(dynamicDefinition, schemas)
+    db.storeToDb(dynamicDefinition, fixedData)
+  } else {
+    db.storeToDb(tableDefinition, fixedData)
+  }
 }
 
 const DEFAULT_CONFIG = {
   extensions: [],
   schema: []
 }
 
+async function runPopulateTables (
+  db: IDatabaseAdapter,
+  usedTables: Array<string>,
+  headers: any,
+  schema: any,
+  ast: any
+) {
+  if (process.env.BULK_FETCH) {
+    await populateTablesInOneHTTPRequest(
+      db,
+      usedTables,
+      headers,
+      schema,
+      ast
+    )
+  } else {
+    await populateTables(
+      db,
+      usedTables,
+      headers,
+      schema,
+      ast
+    )
+  }
+}
+
 async function executor (
   sql: string,
   parameters: Parameters,
@@ -153,7 +233,7 @@ async function executor (
     const headersWithHost = getHost() ? { ...headers, host: getHost() } : { ...headers }
     headersWithHost['user-agent'] = `tentaclesql/${version}`
 
-    await populateTables(
+    await runPopulateTables(
       db,
       usedTables,
       headers,