python - cx_Oracle executemany 与 CLOB

Question

我正在尝试解析多个 CSV 并使用 cx_Oracle 将它们的数据插入到表中。我使用 execute 插入表没有问题，但是当我尝试使用 executemany 执行相同的过程时，出现错误。我使用 execute 的代码是

with open(key,'r') as file:
    for line in file:
        data = data.split(",")
        query = "INSERT INTO " + tables[key] + " VALUES ("
        for col in range(len(data)):
            query += ":" + str(col) + ","
        query = query[:-1] + ")"            
        cursor.execute(query, data)

但是当我用

替换它时

with open(key,'r') as file:
    list = []
    for line in file:
        data = data.split(",")
        list.append(data)
    if len(list) > 0:
        query = "INSERT INTO " + tables[key] + " VALUES ("
        for col in range(len(data)):
            query += ":" + str(col) + ","
        query = query[:-1] + ")"            
        cursor.prepare(query)
        cursor.executemany(None,list)

当我尝试插入到具有 CLOB 列且数据超过 4000 字节的表时，出现“ValueError:字符串数据太大”。当表没有 CLOB 列时，Executemany 工作得很好。有什么方法可以让 cx_Oracle 在执行 executemany 时将适当的列视为 CLOB？

Answer 1

尝试将大列的输入大小设置为 cx_Oracle.CLOB。如果您有二进制数据，则可能不起作用，但应该适用于 CSV 中的任何文本。 2K 值可能低于所需值。

请注意，当涉及 CLOB 列时，executemany 似乎要慢很多，但仍然比重复执行要好:

def _executemany(cursor, sql, data):
    '''
    run the parameterized sql with the given dataset using cursor.executemany 
    if any column contains string values longer than 2k, use CLOBS to avoid "string
    too large" errors.

    @param sql parameterized sql, with parameters named according to the field names in data
    @param data array of dicts, one per row to execute.  each dict must have fields corresponding
                to the parameter names in sql
    '''
    input_sizes = {}
    for row in data:
        for k, v in row.items():
            if isinstance(v, basestring) and len(v) > 2000:
                input_sizes[k] = cx_Oracle.CLOB
    cursor.setinputsizes(**input_sizes)
    cursor.executemany(sql, data)