wal_prefetch.sh: Script pra agilizar a cópia do `restore_command`, trazendo vários arquivos de cada vez

wal_prefetch.sh

#!/bin/bash

# Ideia original do @matheusoliveira
# $1 é %f, $2 é %p

## IMPORTANTE: Lembrar de configurar o `archive_cleanup_command` no `recovery.conf` pra
##             chamar o pg_archivecleanup e apontar pro ${CACHE_DIR}
##   exemplo:
###      restore_command = '/opt/resources/wal_prefetch.sh %f %p'
###      archive_cleanup_command = '/usr/pgsql-9.3/bin/pg_archivecleanup /slave/wal-cache %r'


MAX_FILES=25
REMOTE_DIR='/dados/archive_log'
CACHE_DIR='/slave/wal-cache'
WAL_FILE="${1}"
WAL_PATH="${2}"

if [ -f ${CACHE_DIR}/${WAL_FILE}.gz ]; then
    zcat ${CACHE_DIR}/${WAL_FILE}.gz > ${WAL_PATH}
    exit $?
else
    file_list="/tmp/file_list.txt"
    rm -f ${file_list}
    ssh server "ls -lto ${REMOTE_DIR}" | grep -B ${MAX_FILES} ${WAL_FILE} | awk '{print $NF}' > ${file_list}
    rsync -a --files-from="${file_list}" server:"${REMOTE_DIR}" "${CACHE_DIR}"
    zcat ${CACHE_DIR}/${WAL_FILE}.gz > ${WAL_PATH}
    exit $?
fi