我有抛出这个异常的源码数据库上运行的SQL查询：java.lang.IllegalStateException：拿到场插槽从排山坳0 0失败当我打电话：

I have an SQL query running on an 'sqlite' database that is throwing this exception: "java.lang.IllegalStateException: get field slot from row 0 col 0 failed" when I call:

db.rawQuery( "SELECT data FROM session_data WHERE session_id = ?", new String[] { String.format("%d", session_id) } );
if (!cursor.moveToFirst()) return;
bytes[] bytes = cursor.getBlob(0);

列存在，如果我登录使用亚行外壳sqlite3的/path/to/database.db 我可以成功地执行相同的查询。

The column exists, and if I log in using adb shell sqlite3 /path/to/database.db I can successfully execute the same query.

而产生光标显示，与名为数据一栏选择1排。 BLOB的大小约为1.5 MB - 会是呢？我已验证 cursor.GetColumnIndex（数据）返回0，所以列存在。

The resulting cursor shows that there is 1 row selected with 1 column whose name is "data". The size of the blob is about 1.5 MB - could that be it? I have verified that cursor.GetColumnIndex("data") returns 0, so the column exists.

这是在Android 2.1 SDK运行。任何想法？

This is running on Android 2.1 SDK. Any ideas?

推荐答案

问题是，BLOB太大。看来， cursor.getBlob（0）如果BLOB大小超过一兆字节失败。阅读部分的BLOB解决我的问题：

The problem was that the blob was too big. It appears that cursor.getBlob(0) fails if the blob size is over a megabyte. Reading the blob in segments solved my issue:

// get length of blob data
Cursor cursor = db.rawQuery( "SELECT LENGTH(data) AS len FROM table WHERE id = ?", etc);
if (cursor == null || !cursor.moveToFirst()) throw new Exception("failed");
int size = cursor.getInt(cursor.getColumnIndexOrThrow("len"));
cursor.close();

// read a segment of the blob data
cursor = db.rawQuery( "SELECT SUBSTR(data,0,500000) AS partial FROM table WHERE id = ?", etc);
if (cursor == null || !cursor.moveToFirst()) throw new Exception("failed");
byte[] partial = cursor.getBlob(cursor.getColumnIndexOrThrow("partial"));
cursor.close();

// copy partial bytes, repeat until the whole length has been read...