快速递归地在数据库中插入和更新数据时面临内存问题

Posted 2023-03-14

【中文标题】快速递归地在数据库中插入和更新数据时面临内存问题

【英文标题】：Facing memory issue while Recursively inserting and updating data in database in swift

【发布时间】：2016-12-28 10:39:10

【问题描述】：

我正在数据库中插入和更新超过 100000 个数据。我正在使用 libsqlite3 框架。

问题：我面临的是每次插入内存增加到 4-5 mb 并且永远不会被释放。有更好的解决方案吗？

class DataBase

let COMPANY_TABLE_NAME = "CompanyTable"

let fileName = "\(Constants.sharedInstance.DATABASE_NAME).sqlite"
let DBPath :String?

init() 

  DBPath  = FileManagement.sharedInstance.getDocumentFilePath(fileName)


private var dbPointer: OpaquePointer?

  let SQLITE_STATIC = unsafeBitCast(0, to: sqlite3_destructor_type.self)
  let SQLITE_TRANSIENT = unsafeBitCast(-1, to: sqlite3_destructor_type.self)



deinit

    sqlite3_close(dbPointer)



  func openDataBase(dbPath:String) -> OpaquePointer 


    var db: OpaquePointer?

    if sqlite3_open(dbPath, &db) == SQLITE_OK
    
        print("Successfully opened connection to database at \(dbPath)")
    
    else
    
        //call to load database from file system
    
    return db!



func inserttoCompanyTable(org_code: String , dataString:String)



    let insertSql = "INSERT INTO CompanyTable(orgcode,company_data) VALUES (?,?)"

    let insertStatement = prepareStatement(sql: insertSql)

    sqlite3_bind_text(insertStatement, 0, org_code, -1, SQLITE_TRANSIENT)
    sqlite3_bind_text(insertStatement, 1, dataString, -1,SQLITE_TRANSIENT)


    if sqlite3_step(insertStatement) != SQLITE_DONE 

        let errmsg = String(cString: sqlite3_errmsg(insertStatement))
        print("failure inserting foo: \(errmsg)")
    

    sqlite3_finalize(insertStatement)
    sqlite3_close_v2(insertStatement)



func readAllData()-> [Company]


    var companiesArray:[Company] = [Company]()
    let selectQuery = "SELECT * FROM \(COMPANY_TABLE_NAME);"
    let selectStatement = prepareStatement(sql: selectQuery)

    while sqlite3_step(selectStatement) == SQLITE_ROW 

       if let comStr = sqlite3_column_text(selectStatement, 1)
       
        let comString = String(describing: comStr)

        let comOBj = Mapper<Company>().map(JSONString: comString)
        companiesArray.append(comOBj!)
       

    

    return companiesArray



func isCompanyAvailable(org_code:String) -> Bool 



    let selectQuery = "SELECT * FROM \(COMPANY_TABLE_NAME) WHERE \(CompanyTable.orgcode) =?;"
    let selectStatement = prepareStatement(sql: selectQuery)

    sqlite3_bind_text(selectStatement, 0, org_code, -1, SQLITE_TRANSIENT)

    if sqlite3_step(selectStatement) == SQLITE_ROW
    
        return true
    
    else
    
        return false
    



 


func updateTableData(company: Company)-> Bool  

    let objString = company.toJSONString()
    let updateQuery = "UPDATE TABLE \(COMPANY_TABLE_NAME) SET \(CompanyTable.company_data) = \(objString) WHERE \(CompanyTable.orgcode) = \(company.orgCode);"
    let updateStatement = prepareStatement(sql: updateQuery)

    if sqlite3_step(updateStatement) == SQLITE_ROW
    
        return true
    
    else
    
        return false
    




func deleteFromCompanyTable(company:Company) 

     let deleteQuery = "DELETE FROM \(COMPANY_TABLE_NAME) WHERE \(CompanyTable.orgcode) = \(company.orgCode);"
    let deleteStatement = prepareStatement(sql: deleteQuery)

    if sqlite3_step(deleteStatement) == SQLITE_DONE
    
        print("Successfully deleted row.")
     else 

        print("Could not delete row.")
     



func prepareStatement(sql: String) -> OpaquePointer 
    var statement: OpaquePointer?


    if sqlite3_open(DBPath, &self.dbPointer) == SQLITE_OK
    
        print("Successfully opened connection to database at \(DBPath)")
        if sqlite3_prepare_v2(self.dbPointer, sql, -1, &statement, nil) == SQLITE_OK
        

            return statement!
        
        else
        
            let errmsg = String(cString: sqlite3_errmsg(statement))
            print("error preparing select: \(errmsg)")
        
    


    return statement!

【问题讨论】：

顺便说一句，在您正确调用sqlite3_finalize 的地方，即在inserttoCompanyTable 中，您也使用该语句调用sqlite3_close_v2，这是不正确的。你不应该“关闭”一个声明。只需“完成”它，您就完成了该声明。我们关闭数据库，而不是语句。

还要记住，sqlite3_bind_XXX 调用采用从 1 开始的索引，而不是从 0 开始的索引。 sqlite3_column_XXX 调用使用从零开始的索引，但不是 sqlite3_bind_XXX API。

【参考方案1】：

您将泄漏内存，因为您的大多数sqlite3_prepare_v2 调用没有跟随相应的sqlite3_finalize 调用。每次成功准备 SQL 语句时，都必须确保在完成该语句后完成该语句。