Wrong result for count(*) in hive table

Question

I have created a table in HIVE

CREATE TABLE IF NOT EXISTS daily_firstseen_analysis (
    firstSeen         STRING,
    category          STRING,
    circle            STRING,
    specId            STRING,
    language          STRING,
    osType            STRING,
    count             INT)
    PARTITIONED BY  (day STRING)
    ROW FORMAT DELIMITED
    FIELDS TERMINATED BY '\t'
    STORED AS orc;

count(*) is not giving me correct result for this table

hive> select count(*) from daily_firstseen_analysis;
OK
75
Time taken: 0.922 seconds, Fetched: 1 row(s)

While the number of rows in this table is 959 rows

hive> select * from daily_firstseen_analysis;
....
Time taken: 0.966 seconds, Fetched: 959 row(s)

it gives data with 959 rows

hive> ANALYZE TABLE daily_firstseen_analysis PARTITION(day) COMPUTE STATISTICS noscan; 
    Partition logdata.daily_firstseen_analysis{day=20140521} stats: [numFiles=6, numRows=70, totalSize=4433, rawDataSize=37202]
    Partition logdata.daily_firstseen_analysis{day=20140525} stats: [numFiles=6, numRows=257, totalSize=4937, rawDataSize=136385]
    Partition logdata.daily_firstseen_analysis{day=20140523} stats: [numFiles=6, numRows=211, totalSize=5059, rawDataSize=112140]
    Partition logdata.daily_firstseen_analysis{day=20140524} stats: [numFiles=6, numRows=280, totalSize=5257, rawDataSize=148808]
    Partition logdata.daily_firstseen_analysis{day=20140522} stats: [numFiles=6, numRows=141, totalSize=4848, rawDataSize=74938]
    OK
    Time taken: 5.098 seconds

I am using hive with version Hive 0.13.0.2.1.2.0-402

NOTE: I found this issue in count(*) if We are inserting into a table in more than one time. Tables created with single insert do not have this issue

Answer 1

I execute ANALYZE TABLE ... at first is OK, but raise error when i try again.so i try:

hive> REFRESH TABLE daily_firstseen_analysis;
hive> SELECT COUNT(*) FROM daily_firstseen_analysis;

this is explain

Answer 2

I had the same problem, and using ANALYZE fixed it. Running these commands in order should give you the correct count:

hive> ANALYZE TABLE daily_firstseen_analysis PARTITION(day) COMPUTE STATISTICS;
hive> SELECT COUNT(*) FROM daily_firstseen_analysis;

i.e. you have to use the analyze command before the count. You have half the answer within your question.

Answer 3

if you have an external table, remove all the files in HDFS, and insert into the table again then select count(*) will be incorrect.