python berkeley DB操作——打开btree索引文件中的database

打开BDB中某个索引中的数据库代码：

from bsddb3 import db

import bsddb3 as bsddb

print db.DB_VERSION_STRING

mydb = db.DB()

mydb.open('your_btree_db_filename', 'databsename', dbtype=db.DB_BTREE)

rec = cur.first()

while rec:

    #print key value

    print int(rec[0].encode('hex'), 16), "=>", len(rec[1])

    rec = cur.next()

mydb.close()

注意：同一个db file中可能有多个database！

这样就和 /usr/local/BerkeleyDB.6.1/bin/db_dump your_btree_db_filename 结果一样了，dump结果如下所示：

VERSION=3

format=bytevalue

database=BLOCK_TIME_RANGE

type=btree

duplicates=1

db_pagesize=4096

HEADER=END

DATA=END

VERSION=3

format=bytevalue

database=xxxxyour databse name

type=btree

duplicates=1

db_pagesize=4096

HEADER=END

 01000000  #=>key

 5e096909f0fxxxxx # value

 01000001  #=>key

 5e096809f0ffff83xxxxxxx # value
xxxxxxxxxxxx more btree data xxxxxxxxxxxx

顺便补充，查看一个db中有多少数据库：

bdb = bsddb.btopen('32_20170228151803_qsb.idx', 'r')

print bdb.keys()

bdb.close()

再补充，打开reco DB示例：

from bsddb3 import db

import bsddb3 as bsddb

print db.DB_VERSION_STRING

mydb = db.DB()

mydb.open('30_20170228145149_qsb.db',dbtype=db.DB_RECNO)

cur = mydb.cursor()

i = 0

f = open("data.bin", "wb")

rec = cur.first()

while rec:

    #print rec

    print rec[0], type(rec[1])

    f.write(rec[1]) # write data to file

    rec = cur.next()

    i += 1

f.close()

mydb.close()