The question of whether a database has enough redo logs available is quite common. The documentation suggests to use FAST_START_MTTR_TARGET and V$INSTANCE_RECOVERY.OPTIMAL_LOGFILE_SIZE to identify “the optimal” redo log size based on the target recovery time. I’ve never used it and can’t comment if it is a correct/reasonable way or not. The easiest way to identify if you need to increase the redo log files size is to check for ‘log file switch (checkpoint incomplete)’ waits, and, depending on the total wait time, decide how much more redo you need. The obvious source of such information is Statspack or AWR. I have written a query which pulls the necessary information and calculates the amount of redo you need to add based on the total wait time.
Here is the query and an example output from 10.2.0.4 database:
set pagesize 50000 linesize 300
col instance_number format 99 head 'In|st'
col tim head 'Period end'
col cpu_sec format 999,999,999.9 head 'CPU used|sec'
col phy_reads format 999,999,999 head 'Physical|reads'
col phy_writes format 999,999,999 head 'Physical|writes'
col cr_served format 999,999,999 head 'CR blocks|served'
col current_served format 999,999,999 head 'CUR blocks|served'
col redo_mb format 999,999,999.9 head 'Redo, MB'
col processes format 999,999 head 'Proc|esses'
col avg_df_seq format 9,999.9 head 'Avg 1|read'
col avg_df_scat format 9,999.9 head 'Avg N|read'
col redo_diff_to_md_pct format 999,999 head 'Redo Diff|to median, %'
col avg_lfpw format 999.99 head 'Avg|LFPW'
col avg_log_sync format 9,999.99 head 'Avg Log|Sync, ms'
col log_ckpt_sec format 999,999 head 'CKPT|waits, s'
col redo_needed format 999,999 head 'Redo to|Add, MB'
compute max of cpu_sec on instance_number
compute max of phy_reads on instance_number
compute max of phy_writes on instance_number
compute max of cr_served on instance_number
compute max of current_served on instance_number
compute max of phy_writes on instance_number
compute max of redo_needed on instance_number
compute max of log_ckpt_sec on instance_number
compute max of avg_log_sync on instance_number
compute max of avg_lfpw on instance_number
compute max of redo_mb on instance_number
compute max of processes on instance_number
compute max of avg_df_seq on instance_number
compute max of avg_df_scat on instance_number
break on instance_number skip page
with t_interval as
(
select /*+ inline */ sysdate-30 begin, sysdate as end from dual
)
select
stats.dbid dbid,
stats.instance_number instance_number,
to_char(stats.snap_time, 'YYYYMMDD HH24MI') tim,
stats.cpu_used / 100 cpu_sec,
stats.phy_reads phy_reads,
stats.phy_writes phy_writes,
stats.cr_served cr_served,
stats.current_served current_served,
stats.redo_size / 1024 / 1024 redo_mb,
procs.current_utilization processes,
--
waits.df_seq_micro / 1000 / nullif(waits.df_seq_waits,0) avg_df_seq,
waits.df_scat_micro / 1000 / nullif(waits.df_scat_waits,0) avg_df_scat,
(stats.redo_size - stats.md_redo_size) * 100 / stats.md_redo_size redo_diff_to_md_pct,
stats.redo_write_time*10/stats.redo_writes avg_lfpw,
waits.log_sync_micro/nullif(waits.log_sync_waits, 0) / 1000 avg_log_sync,
waits.log_ckpt_micro/1e6 log_ckpt_sec,
( stats.redo_size /
( nullif(waits.snap_interval, 0) * 86400 ) ) *
( waits.log_ckpt_micro/1e6 ) / 1024 / 1024 redo_needed,
stats.is_restart
from
(
select
snap_id,
snap_time,
snap_interval,
instance_number,
dbid,
log_sync_micro,
log_sync_waits,
log_ckpt_micro,
log_ckpt_waits,
df_seq_micro,
df_seq_waits,
df_scat_micro,
df_scat_waits,
direct_micro,
direct_waits,
median(log_sync_micro/nullif(log_sync_waits, 0)) over (partition by dbid, instance_number) md_log_sync_micro
from
(
select
snap_id,
snap_time,
instance_number,
dbid,
max(snap_interval) snap_interval,
max(decode(event, 'log file sync', wait_micro)) log_sync_micro,
max(decode(event, 'log file sync', total_waits)) log_sync_waits,
max(decode(event, 'log file switch (checkpoint incomplete)', wait_micro)) log_ckpt_micro,
max(decode(event, 'log file switch (checkpoint incomplete)', total_waits)) log_ckpt_waits,
max(decode(event, 'db file sequential read', wait_micro)) df_seq_micro,
max(decode(event, 'db file sequential read', total_waits)) df_seq_waits,
max(decode(event, 'db file scattered read', wait_micro)) df_scat_micro,
max(decode(event, 'db file scattered read', total_waits)) df_scat_waits,
max(decode(event, 'direct path read', wait_micro)) direct_micro,
max(decode(event, 'direct path read', total_waits)) direct_waits
from
(
select
e.snap_id,
e.instance_number,
e.dbid,
sn.snap_time,
snap_time - lag(snap_time) over (partition by e.dbid, e.instance_number, e.event order by sn.snap_time) snap_interval,
sn.startup_time,
e.event,
case when (sn.snap_time >= sn.startup_time and lag(sn.snap_time) over (partition by e.dbid, e.instance_number, e.event order by sn.snap_time) < sn.startup_time)
then e.time_waited_micro
else e.time_waited_micro - lag(e.time_waited_micro) over (partition by e.dbid, e.instance_number, e.event order by sn.snap_time)
end wait_micro,
case when (sn.snap_time >= sn.startup_time and lag(sn.snap_time) over (partition by e.dbid, e.instance_number, e.event order by sn.snap_time) < sn.startup_time)
then e.total_waits
else e.total_waits - lag(e.total_waits) over (partition by e.dbid, e.instance_number, e.event order by sn.snap_time)
end total_waits
from
stats$system_event e,
stats$snapshot sn,
t_interval t
where
sn.snap_id = e.snap_id and
sn.dbid = e.dbid and
sn.instance_number = e.instance_number and
sn.snap_time between t.begin and t.end and
e.event in (
'log file sync',
'log file switch (checkpoint incomplete)',
'db file sequential read',
'db file scattered read',
'direct path read'
)
)
group by dbid, instance_number, snap_time, snap_id
)
) waits,
(
select
snap_id,
snap_time,
instance_number,
dbid,
redo_size,
redo_write_time,
redo_writes,
is_restart,
cpu_used,
phy_reads,
phy_reads_cache,
phy_writes,
phy_writes_cache,
cr_served,
current_served,
median(redo_size) over (partition by dbid, instance_number) md_redo_size
from
(
select
snap_id,
snap_time,
instance_number,
dbid,
max(is_restart) is_restart,
max(decode(name, 'redo size', stat_diff)) redo_size,
max(decode(name, 'redo write time', stat_diff)) redo_write_time,
max(decode(name, 'redo writes', stat_diff)) redo_writes,
max(decode(name, 'CPU used by this session', stat_diff)) cpu_used,
max(decode(name, 'physical read total IO requests', stat_diff)) phy_reads,
max(decode(name, 'physical reads cache', stat_diff)) phy_reads_cache,
max(decode(name, 'physical write total IO requests',stat_diff)) phy_writes,
max(decode(name, 'physical writes from cache', stat_diff)) phy_writes_cache,
max(decode(name, 'gc cr blocks served', stat_diff)) cr_served,
max(decode(name, 'gc current blocks served', stat_diff)) current_served
from
(
select
stats.snap_id,
stats.instance_number,
stats.dbid,
sn.snap_time,
sn.startup_time,
n.name,
case when (sn.snap_time >= sn.startup_time and lag(sn.snap_time) over (partition by stats.dbid, stats.instance_number, stats.statistic# order by sn.snap_time) < sn.startup_time)
then stats.value
else stats.value - lag(stats.value) over (partition by stats.dbid, stats.instance_number, stats.statistic# order by stats.snap_id)
end stat_diff,
case when (sn.snap_time >= sn.startup_time and lag(sn.snap_time) over (partition by stats.dbid, stats.instance_number, stats.statistic# order by sn.snap_time) < sn.startup_time)
then 'Yes'
end is_restart
from
stats$sysstat stats,
stats$snapshot sn,
v$statname n,
t_interval t
where
sn.snap_id = stats.snap_id and
sn.dbid = stats.dbid and
sn.instance_number = stats.instance_number and
sn.snap_time between t.begin and t.end and
stats.statistic# = n.statistic# and
n.name in (
'redo size',
'redo write time',
'redo writes',
'CPU used by this session',
'physical read total IO requests',
'physical reads cache',
'physical write total IO requests',
'physical writes from cache',
'gc cr blocks served',
'gc current blocks served'
)
)
group by dbid, instance_number, snap_time, snap_id
)
) stats,
(
select
stats.snap_id,
stats.instance_number,
stats.dbid,
stats.resource_name,
stats.current_utilization
from
stats$resource_limit stats,
stats$snapshot sn,
t_interval t
where
sn.snap_id = stats.snap_id and
sn.dbid = stats.dbid and
sn.instance_number = stats.instance_number and
sn.snap_time between t.begin and t.end and
stats.resource_name = 'processes'
) procs
where
waits.dbid = stats.dbid and
waits.instance_number = stats.instance_number and
waits.snap_id = stats.snap_id and
waits.dbid = procs.dbid and
waits.instance_number = procs.instance_number and
waits.snap_id = procs.snap_id
order by
stats.dbid, stats.instance_number, stats.snap_time
;
Redo Diff Avg Avg Log CKPT Redo to Period end Redo, MB to median, % LFPW Sync, ms waits, s Add, MB IS_ ------------- -------------- ------------ ------- --------- -------- -------- --- 20131213 0800 20131213 0900 3,659.1 21 2.77 8.73 63 64 20131213 1000 4,964.8 64 15.06 15.45 90 125 20131213 1100 3,533.0 17 26.42 9.43 114 112 20131213 1200 206.5 -93 10.86 3.83 0 0 20131213 1300 1,363.5 -55 34.17 10.65 26 10 20131213 1400 133.4 -96 9.17 4.07 0 0 20131213 1500 123.7 -96 8.52 4.62 0 0 20131213 1600 2,037.8 -33 36.22 8.73 40 23 20131213 1700 13.6 -100 3.82 8.43 0 0 20131213 1800 60.7 -98 91.51 251.81 Yes 20131213 1900 4,177.9 38 6.67 53.66 52 30 20131213 2000 3,145.3 4 39.61 12.79 41 35 20131213 2100 4,606.2 52 19.65 7.90 63 80 20131213 2200 3,303.8 9 77.90 115.53 73 67 20131213 2300 2,673.2 -12 57.37 85.43 123 91 20131214 0000 1,213.9 -60 56.35 155.38 83 28 20131214 0100 3,569.0 18 110.49 304.81 121 120 20131214 0200 5,587.7 84 17.92 26.62 123 191 20131214 0300 7,630.4 152 30.87 28.08 138 293 20131214 0400 5,706.7 88 37.36 39.41 179 284 20131214 0500 7,688.8 154 42.66 26.86 196 419 20131214 0600 1,377.6 -55 29.46 19.79 29 11 20131214 0700 2,176.3 -28 26.62 24.13 43 26 20131214 0800 2,179.6 -28 25.23 22.50 43 26 20131214 0900 3,892.0 28 2.54 14.32 93 101 20131214 1000 5,354.2 77 32.67 20.26 127 189 20131214 1100 4,232.6 40 49.24 86.27 108 127 20131214 1200 1,778.2 -41 25.76 10.03 29 14 20131214 1300 23.0 -99 4.07 6.14 0 0 20131214 1400 1,378.1 -55 32.63 14.99 23 9 20131214 1500 2,121.7 -30 34.60 285.24 38 22 20131214 1600 701.6 -77 39.29 9.90 7 1 20131214 1700 1,557.5 -49 43.51 52.96 24 10 20131214 1800 455.3 -85 35.41 57.68 1 0 20131214 1900 4,175.1 38 7.22 22.67 71 82 20131214 2000 3,116.7 3 45.78 20.85 72 63 20131214 2100 4,578.1 51 27.92 7.34 68 86 20131214 2200 3,751.4 24 22.54 25.00 73 76 20131214 2300 1,962.1 -35 52.08 46.90 33 18 20131215 0000 3,161.0 4 32.76 67.61 60 53 20131215 0100 6,516.9 115 46.88 52.77 147 267 20131215 0200 3,147.0 4 17.63 35.01 112 98 20131215 0300 5,084.3 68 50.88 95.94 164 232 20131215 0400 5,727.6 89 56.45 49.84 143 228 20131215 0500 7,783.3 157 59.43 53.49 198 428 20131215 0600 1,828.4 -40 68.17 136.70 46 23 20131215 0700 840.2 -72 39.24 8.99 20 5 20131215 0800 2,202.9 -27 28.78 28.14 42 26 20131215 0900 3,704.2 22 2.53 17.06 80 82 20131215 1000 4,847.2 60 32.70 57.14 6 8 20131215 1100 2,987.0 -1 29.51 9.84 0 0 20131215 1200 203.2 -93 16.36 10.84 0 0 20131215 1300 42.3 -99 1.12 2.00 0 0 20131215 1400 596.7 -80 9.57 12.94 0 0 20131215 1500 186.8 -94 10.67 11.89 Yes 20131215 1600 942.0 -69 7.57 17.27 20131215 1700 14.5 -100 1.82 3.56 20131215 1800 462.6 -85 9.31 8.47 20131215 1900 3,762.0 24 4.79 8.23 20131215 2000 3,171.9 5 34.83 16.26 20131215 2100 4,525.7 49 28.30 6.52 20131215 2200 3,623.0 20 18.74 21.89 1 0 20131215 2300 2,625.7 -13 42.53 12.18 0 0 20131216 0000 2,256.5 -26 39.12 41.47 0 0 20131216 0100 6,061.9 100 93.86 129.36 11 19 20131216 0200 6,297.2 108 19.90 30.07 0 0 20131216 0300 5,079.6 68 23.35 59.40 0 0 20131216 0400 5,555.2 83 38.73 34.99 0 0 20131216 0500 7,560.7 150 46.22 61.08 0 0 20131216 0600 1,364.1 -55 35.62 34.54 0 0 20131216 0700 2,212.2 -27 35.83 16.32 0 0 20131216 0800 2,117.8 -30 25.73 12.24 0 0 20131216 0900 3,684.7 22 40.42 28.94 0 0 20131216 1000 6,502.9 115 5.65 29.35 0 1 20131216 1100 4,372.9 44 29.11 14.23 0 0 20131216 1200 1,742.8 -42 25.10 12.52 0 0 20131216 1300 31.1 -99 5.92 12.56 0 0 20131216 1400 1,486.6 -51 44.12 11.59 0 0 20131216 1500 6,108.9 102 36.05 38.18 0 0 20131216 1600 686.5 -77 27.43 7.14 0 0 20131216 1700 1,557.2 -49 22.99 7.41 0 0 20131216 1800 464.3 -85 26.43 25.12 0 0 20131216 1900 3,974.1 31 4.59 9.26 6 6 20131216 2000 3,102.7 2 30.15 28.33 0 0 20131216 2100 5,400.9 78 20.70 8.15 0 0 20131216 2200 3,130.8 3 11.57 15.79 0 0 20131216 2300 2,203.7 -27 48.37 63.28 0 0 20131217 0000 3,098.9 2 29.81 52.57 0 0 20131217 0100 3,909.3 29 71.10 169.28 0 0 20131217 0200 6,227.8 106 19.69 30.72 0 0 20131217 0300 7,325.3 142 27.64 45.12 0 0 20131217 0400 6,068.9 100 37.96 37.70 0 0 20131217 0500 7,231.6 139 35.11 26.07 0 0 20131217 0600 1,263.5 -58 24.18 13.22 0 0 20131217 0700 2,019.4 -33 25.45 5.84 0 0 20131217 0800 2,130.4 -30 22.27 12.88 0 0 20131217 0900 4,018.1 33 5.33 58.09 0 0 20131217 1000 5,193.5 71 6.36 63.90 2 3 20131217 1100 3,217.3 6 25.76 11.66 0 0 20131217 1200 1,779.8 -41 21.45 8.97 0 0 20131217 1300 734.1 -76 20.19 5.34 0 0 20131217 1400 2,697.0 -11 24.35 8.52 0 0 20131217 1500 122.0 -96 36.35 18.74 0 0 20131217 1600 817.4 -73 29.34 7.29 0 0 20131217 1700 1,616.1 -47 22.52 8.10 0 0 20131217 1800 466.8 -85 43.67 73.78 0 0 20131217 1900 3,915.3 29 4.58 10.88 0 0 20131217 2000 3,082.5 2 35.76 21.84 0 0 20131217 2100 5,320.9 76 20.40 8.94 0 0 20131217 2200 3,020.1 -0 52.09 44.66 1 1 20131217 2300 2,034.3 -33 43.56 62.13 0 0 20131218 0000 2,723.5 -10 30.35 51.05 0 0 20131218 0100 4,740.9 56 61.93 124.11 0 0 20131218 0200 7,426.3 145 19.91 32.82 0 0 20131218 0300 4,703.2 55 21.78 28.80 0 0 20131218 0400 5,658.4 87 37.75 20.70 0 0 20131218 0500 7,858.4 159 42.53 29.13 0 0 20131218 0600 1,304.4 -57 30.40 9.91 0 0 20131218 0700 2,143.6 -29 28.20 13.88 1 1 20131218 0800 2,078.0 -31 24.94 18.97 0 0 20131218 0900 3,833.6 27 4.17 22.95 2 2 20131218 1000 5,933.3 96 10.73 19.28 0 0 20131218 1100 2,533.8 -16 23.92 11.09 0 0 20131218 1200 1,775.0 -41 21.39 9.89 0 0 20131218 1300 31.5 -99 3.95 4.02 0 0 20131218 1400 1,916.7 -37 28.73 15.65 0 0 20131218 1500 1,794.5 -41 34.64 215.95 0 0 20131218 1600 876.2 -71 27.94 4.64 0 0 20131218 1700 1,544.7 -49 21.90 6.72 0 0 20131218 1800 465.2 -85 26.04 25.71 0 0 20131218 1900 3,662.1 21 4.19 7.11 0 0 20131218 2000 3,085.3 2 34.51 16.00 0 0 20131218 2100 5,286.9 75 20.71 7.70 0 0 20131218 2200 3,072.3 1 15.16 11.18 0 0 20131218 2300 2,489.8 -18 22.96 17.53 0 0 20131219 0000 2,249.1 -26 31.52 77.49 2 1 20131219 0100 3,466.3 14 169.29 321.38 7 7 20131219 0200 4,365.9 44 11.78 25.60 0 0 20131219 0300 9,837.6 225 32.10 42.25 12 33 20131219 0400 7,251.2 139 42.75 27.18 0 0 20131219 0500 8,428.8 178 40.70 22.69 0 0 20131219 0600 1,304.1 -57 25.98 8.51 0 0 20131219 0700 2,026.6 -33 28.31 14.68 0 0 20131219 0800 2,413.5 -20 8.62 1.15 0 0 20131219 0900 4,025.8 33 3.17 19.64 0 0 ...
This query is large and can print not only redo-related statistics, you just need to uncomment then necessary columns. The columns which are relevant to this post are “CKPT waits, s” and “Redo To Add, MB”. First is total time wasted due to ‘log file switch (checkpoint incomplete)’ waits, and the second is the projected additional amount of redo which might have been enough to reduce the waits down to minimum. When calculating this projected size, the average redo rate per hour is used which is then multiplied by the total time waited. Of course this is an incorrect approximation: if you had 10 sessions waiting for the checkpoint to complete, then the total time waited by sessions is obviously more than wall clock time, which means that multiplying it by an average redo rate is totally wrong; but it is almost correct with a database that at any point in time has only 1 session waiting for checkpoint to complete. Nevertheless I think this approximation is a good starting point.
In this particular case, the database had 4 groups of redo of 60MB each, and on December 15th it has been changed to 4 groups of 150MB each. As you can see it helped to reduce the number of ‘checkpoint incomplete’ waits significantly, although not completely. If you look at the redo rate per hour, it is clear that after the redo log size change the rate of database changes has also increased, so the waits are somewhat consequence of the ability to generate more changes per second now.
And just for the sake of completeness here is a version of this query for AWR. I didn’t test it much but it should be fine as most things are similar to Statspack tables. Enjoy!
set pagesize 50000 linesize 300
col instance_number format 99 head 'In|st'
col tim head 'Period end'
col cpu_sec format 999,999,999.9 head 'CPU used|sec'
col phy_reads format 999,999,999 head 'Physical|reads'
col phy_writes format 999,999,999 head 'Physical|writes'
col cr_served format 999,999,999 head 'CR blocks|served'
col current_served format 999,999,999 head 'CUR blocks|served'
col redo_mb format 999,999,999.9 head 'Redo, MB'
col processes format 999,999 head 'Proc|esses'
col avg_df_seq format 9,999.9 head 'Avg 1|read'
col avg_df_scat format 9,999.9 head 'Avg N|read'
col redo_diff_to_md_pct format 999,999 head 'Redo Diff|to median, %'
col avg_lfpw format 999.99 head 'Avg|LFPW'
col avg_log_sync format 9,999.99 head 'Avg Log|Sync, ms'
col log_ckpt_sec format 999,999 head 'CKPT|waits, s'
col redo_needed format 999,999 head 'Redo to|Add, MB'
compute max of cpu_sec on instance_number
compute max of phy_reads on instance_number
compute max of phy_writes on instance_number
compute max of cr_served on instance_number
compute max of current_served on instance_number
compute max of phy_writes on instance_number
compute max of redo_needed on instance_number
compute max of log_ckpt_sec on instance_number
compute max of avg_log_sync on instance_number
compute max of avg_lfpw on instance_number
compute max of redo_mb on instance_number
compute max of processes on instance_number
compute max of avg_df_seq on instance_number
compute max of avg_df_scat on instance_number
break on instance_number skip page
with t_interval as
(
select /*+ inline */ sysdate-30 begin, sysdate as end from dual
)
select
stats.dbid dbid,
stats.instance_number instance_number,
to_char(stats.begin_interval_time, 'YYYYMMDD HH24MI') tim,
stats.cpu_used / 100 cpu_sec,
stats.phy_reads phy_reads,
stats.phy_writes phy_writes,
stats.cr_served cr_served,
stats.current_served current_served,
stats.redo_size / 1024 / 1024 redo_mb,
procs.current_utilization processes,
--
waits.df_seq_micro / 1000 / nullif(waits.df_seq_waits,0) avg_df_seq,
waits.df_scat_micro / 1000 / nullif(waits.df_scat_waits,0) avg_df_scat,
(stats.redo_size - stats.md_redo_size) * 100 / stats.md_redo_size redo_diff_to_md_pct,
stats.redo_write_time*10/stats.redo_writes avg_lfpw,
waits.log_sync_micro/nullif(waits.log_sync_waits, 0) / 1000 avg_log_sync,
waits.log_ckpt_micro/1e6 log_ckpt_sec,
( stats.redo_size /
( waits.snap_interval * 86400 ) ) *
( waits.log_ckpt_micro/1e6 ) / 1024 / 1024 redo_needed,
stats.is_restart
from
(
select
snap_id,
begin_interval_time,
snap_interval,
instance_number,
dbid,
log_sync_micro,
log_sync_waits,
log_ckpt_micro,
log_ckpt_waits,
df_seq_micro,
df_seq_waits,
df_scat_micro,
df_scat_waits,
direct_micro,
direct_waits,
median(log_sync_micro/nullif(log_sync_waits, 0)) over (partition by dbid, instance_number) md_log_sync_micro
from
(
select
snap_id,
begin_interval_time,
instance_number,
dbid,
max(snap_interval) snap_interval,
max(decode(event_name, 'log file sync', wait_micro)) log_sync_micro,
max(decode(event_name, 'log file sync', total_waits)) log_sync_waits,
max(decode(event_name, 'log file switch (checkpoint incomplete)', wait_micro)) log_ckpt_micro,
max(decode(event_name, 'log file switch (checkpoint incomplete)', total_waits)) log_ckpt_waits,
max(decode(event_name, 'db file sequential read', wait_micro)) df_seq_micro,
max(decode(event_name, 'db file sequential read', total_waits)) df_seq_waits,
max(decode(event_name, 'db file scattered read', wait_micro)) df_scat_micro,
max(decode(event_name, 'db file scattered read', total_waits)) df_scat_waits,
max(decode(event_name, 'direct path read', wait_micro)) direct_micro,
max(decode(event_name, 'direct path read', total_waits)) direct_waits
from
(
select
e.snap_id,
e.instance_number,
e.dbid,
sn.begin_interval_time,
cast(begin_interval_time as date) - cast(lag(begin_interval_time) over (partition by e.dbid, e.instance_number, e.event_name order by sn.begin_interval_time) as date) snap_interval,
sn.startup_time,
e.event_name,
case when (sn.begin_interval_time >= sn.startup_time and lag(sn.begin_interval_time) over (partition by e.dbid, e.instance_number, e.event_name order by sn.begin_interval_time) < sn.startup_time)
then e.time_waited_micro
else e.time_waited_micro - lag(e.time_waited_micro) over (partition by e.dbid, e.instance_number, e.event_name order by sn.begin_interval_time)
end wait_micro,
case when (sn.begin_interval_time >= sn.startup_time and lag(sn.begin_interval_time) over (partition by e.dbid, e.instance_number, e.event_name order by sn.begin_interval_time) < sn.startup_time)
then e.total_waits
else e.total_waits - lag(e.total_waits) over (partition by e.dbid, e.instance_number, e.event_name order by sn.begin_interval_time)
end total_waits
from
dba_hist_system_event e,
dba_hist_snapshot sn,
t_interval t
where
sn.snap_id = e.snap_id and
sn.dbid = e.dbid and
sn.instance_number = e.instance_number and
sn.begin_interval_time between t.begin and t.end and
e.event_name in (
'log file sync',
'log file switch (checkpoint incomplete)',
'db file sequential read',
'db file scattered read',
'direct path read'
)
)
group by dbid, instance_number, begin_interval_time, snap_id
)
) waits,
(
select
snap_id,
begin_interval_time,
instance_number,
dbid,
redo_size,
redo_write_time,
redo_writes,
is_restart,
cpu_used,
phy_reads,
phy_reads_cache,
phy_writes,
phy_writes_cache,
cr_served,
current_served,
median(redo_size) over (partition by dbid, instance_number) md_redo_size
from
(
select
snap_id,
begin_interval_time,
instance_number,
dbid,
max(is_restart) is_restart,
max(decode(stat_name, 'redo size', stat_diff)) redo_size,
max(decode(stat_name, 'redo write time', stat_diff)) redo_write_time,
max(decode(stat_name, 'redo writes', stat_diff)) redo_writes,
max(decode(stat_name, 'CPU used by this session', stat_diff)) cpu_used,
max(decode(stat_name, 'physical read total IO requests', stat_diff)) phy_reads,
max(decode(stat_name, 'physical reads cache', stat_diff)) phy_reads_cache,
max(decode(stat_name, 'physical write total IO requests',stat_diff)) phy_writes,
max(decode(stat_name, 'physical writes from cache', stat_diff)) phy_writes_cache,
max(decode(stat_name, 'gc cr blocks served', stat_diff)) cr_served,
max(decode(stat_name, 'gc current blocks served', stat_diff)) current_served
from
(
select
stats.snap_id,
stats.instance_number,
stats.dbid,
sn.begin_interval_time,
sn.startup_time,
stats.stat_name,
case when (sn.begin_interval_time >= sn.startup_time and lag(sn.begin_interval_time) over (partition by stats.dbid, stats.instance_number, stats.stat_id order by sn.begin_interval_time) < sn.startup_time)
then stats.value
else stats.value - lag(stats.value) over (partition by stats.dbid, stats.instance_number, stats.stat_id order by stats.snap_id)
end stat_diff,
case when (sn.begin_interval_time >= sn.startup_time and lag(sn.begin_interval_time) over (partition by stats.dbid, stats.instance_number, stats.stat_id order by sn.begin_interval_time) < sn.startup_time)
then 'Yes'
end is_restart
from
dba_hist_sysstat stats,
dba_hist_snapshot sn,
t_interval t
where
sn.snap_id = stats.snap_id and
sn.dbid = stats.dbid and
sn.instance_number = stats.instance_number and
sn.begin_interval_time between t.begin and t.end and
stats.stat_name in (
'redo size',
'redo write time',
'redo writes',
'CPU used by this session',
'physical read total IO requests',
'physical reads cache',
'physical write total IO requests',
'physical writes from cache',
'gc cr blocks served',
'gc current blocks served'
)
)
group by dbid, instance_number, begin_interval_time, snap_id
)
) stats,
(
select
stats.snap_id,
stats.instance_number,
stats.dbid,
stats.resource_name,
stats.current_utilization
from
dba_hist_resource_limit stats,
dba_hist_snapshot sn,
t_interval t
where
sn.snap_id = stats.snap_id and
sn.dbid = stats.dbid and
sn.instance_number = stats.instance_number and
sn.begin_interval_time between t.begin and t.end and
stats.resource_name = 'processes'
) procs
where
waits.dbid = stats.dbid and
waits.instance_number = stats.instance_number and
waits.snap_id = stats.snap_id and
waits.dbid = procs.dbid and
waits.instance_number = procs.instance_number and
waits.snap_id = procs.snap_id
order by
stats.dbid, stats.instance_number, stats.begin_interval_time
;