本節(jié)簡(jiǎn)單介紹了PostgreSQL的備份工具pg_basebackup源碼中實(shí)際執(zhí)行備份邏輯的函數(shù)BaseBackup.
創(chuàng)新互聯(lián)建站是專(zhuān)業(yè)的威遠(yuǎn)網(wǎng)站建設(shè)公司，威遠(yuǎn)接單;提供成都網(wǎng)站制作、成都網(wǎng)站建設(shè),網(wǎng)頁(yè)設(shè)計(jì),網(wǎng)站設(shè)計(jì),建網(wǎng)站,PHP網(wǎng)站建設(shè)等專(zhuān)業(yè)做網(wǎng)站服務(wù);采用PHP框架,可快速的進(jìn)行威遠(yuǎn)網(wǎng)站開(kāi)發(fā)網(wǎng)頁(yè)制作和功能擴(kuò)展;專(zhuān)業(yè)做搜索引擎喜愛(ài)的網(wǎng)站,專(zhuān)業(yè)的做網(wǎng)站團(tuán)隊(duì),希望更多企業(yè)前來(lái)合作!
option
使用工具時(shí)存儲(chǔ)選項(xiàng)的數(shù)據(jù)結(jié)構(gòu)
重慶分公司
重慶分公司
#ifndef HAVE_STRUCT_OPTION
//工具軟件選項(xiàng)
struct option
{
const char *name;//名稱(chēng)
int has_arg;//是否包含參數(shù),no_argument/required_argument/optional_argument
int *flag;//標(biāo)記
int val;//參數(shù)值
};
#define no_argument 0
#define required_argument 1
#define optional_argument 2
#endif
/*
* On OpenBSD and some versions of Solaris, opterr and friends are defined in
* core libc rather than in a separate getopt module. Define these variables
* only if configure found they aren't there by default; otherwise, this
* module and its callers will just use libc's variables. (We assume that
* testing opterr is sufficient for all of these.)
*/
#ifndef HAVE_INT_OPTERR
int opterr = 1, /* if error message should be printed */
optind = 1, /* index into parent argv vector */
optopt; /* character checked for validity */
char *optarg; /* argument associated with option */
#endif
#define BADCH (int)'?'
#define BADARG (int)':'
#define EMSG ""
pg_result
用于接收PQgetResult的返回結(jié)果.
struct pg_result
{
//元組數(shù)量
int ntups;
//屬性數(shù)量
int numAttributes;
PGresAttDesc *attDescs;
//PGresTuple數(shù)組
PGresAttValue **tuples; /* each PGresTuple is an array of
* PGresAttValue's */
//元組數(shù)組的大小
int tupArrSize; /* allocated size of tuples array */
//參數(shù)格式
int numParameters;
//參數(shù)描述符
PGresParamDesc *paramDescs;
//執(zhí)行狀態(tài)類(lèi)型(枚舉變量)
ExecStatusType resultStatus;
//從查詢(xún)返回的命令狀態(tài)
char cmdStatus[CMDSTATUS_LEN]; /* cmd status from the query */
//1-二進(jìn)制的元組數(shù)據(jù),否則為文本數(shù)據(jù)
int binary; /* binary tuple values if binary == 1,
* otherwise text */
/*
* These fields are copied from the originating PGconn, so that operations
* on the PGresult don't have to reference the PGconn.
* 這些字段從原始的PGconn中拷貝,以便不需要依賴(lài)PGconn
*/
//鉤子函數(shù)
PGNoticeHooks noticeHooks;
PGEvent *events;
int nEvents;
int client_encoding; /* encoding id */
/*
* Error information (all NULL if not an error result). errMsg is the
* "overall" error message returned by PQresultErrorMessage. If we have
* per-field info then it is stored in a linked list.
* 錯(cuò)誤信息(如沒(méi)有錯(cuò)誤,則全部為NULL)
* errMsg是PQresultErrorMessage返回的"overall"錯(cuò)誤信息.
* 如果存在per-field信息,那么會(huì)存儲(chǔ)在相互鏈接的鏈表中
*/
//錯(cuò)誤信息
char *errMsg; /* error message, or NULL if no error */
//按字段拆分的信息
PGMessageField *errFields; /* message broken into fields */
//如可用,觸發(fā)查詢(xún)的文本信息
char *errQuery; /* text of triggering query, if available */
/* All NULL attributes in the query result point to this null string */
//查詢(xún)結(jié)果中的所有NULL屬性指向該null字符串
char null_field[1];
/*
* Space management information. Note that attDescs and error stuff, if
* not null, point into allocated blocks. But tuples points to a
* separately malloc'd block, so that we can realloc it.
* 空間管理信息.
* 注意attDescs和error,如為not null,則指向已分配的blocks.
* 但元組指向單獨(dú)的已分配的block,因此可以重新分配空間.
*/
//最近已分配的block
PGresult_data *curBlock; /* most recently allocated block */
//塊中空閑空間的開(kāi)始偏移
int curOffset; /* start offset of free space in block */
//塊中剩余的空閑字節(jié)
int spaceLeft; /* number of free bytes remaining in block */
//該P(yáng)Gresult結(jié)構(gòu)體總共的分配空間
size_t memorySize; /* total space allocated for this PGresult */
};
/* Data about a single parameter of a prepared statement */
//prepared statement語(yǔ)句的單個(gè)參數(shù)的數(shù)據(jù)
typedef struct pgresParamDesc
{
//類(lèi)型ID
Oid typid; /* type id */
} PGresParamDesc;
typedef enum
{
//空查詢(xún)串
PGRES_EMPTY_QUERY = 0, /* empty query string was executed */
//后臺(tái)進(jìn)程正常執(zhí)行了沒(méi)有結(jié)果返回的查詢(xún)命令
PGRES_COMMAND_OK, /* a query command that doesn't return
* anything was executed properly by the
* backend */
//后臺(tái)進(jìn)程正常執(zhí)行了有元組返回的查詢(xún)命令
//PGresult中有結(jié)果元組
PGRES_TUPLES_OK, /* a query command that returns tuples was
* executed properly by the backend, PGresult
* contains the result tuples */
//拷貝數(shù)據(jù)OUT,傳輸中
PGRES_COPY_OUT, /* Copy Out data transfer in progress */
//拷貝數(shù)據(jù)IN,傳輸中
PGRES_COPY_IN, /* Copy In data transfer in progress */
//從后臺(tái)進(jìn)程中收到非期望中的響應(yīng)
PGRES_BAD_RESPONSE, /* an unexpected response was recv'd from the
* backend */
//提示或警告信息
PGRES_NONFATAL_ERROR, /* notice or warning message */
//查詢(xún)失敗
PGRES_FATAL_ERROR, /* query failed */
//拷貝I/O,傳輸中
PGRES_COPY_BOTH, /* Copy In/Out data transfer in progress */
//更大的結(jié)果集中的單個(gè)元組
PGRES_SINGLE_TUPLE /* single tuple from larger resultset */
} ExecStatusType;
typedef union pgresult_data PGresult_data;
union pgresult_data
{
//鏈接到下一個(gè)block,或者為NULL
PGresult_data *next; /* link to next block, or NULL */
//以字節(jié)形式訪(fǎng)問(wèn)塊
char space[1]; /* dummy for accessing block as bytes */
};
BaseBackup,實(shí)際執(zhí)行備份的函數(shù).
主要邏輯是通過(guò)libpq接口向服務(wù)器端發(fā)起備份請(qǐng)求(BASE_BACKUP命令)
static void
BaseBackup(void)
{
PGresult *res;
char *sysidentifier;
TimeLineID latesttli;
TimeLineID starttli;
char *basebkp;
char escaped_label[MAXPGPATH];
char *maxrate_clause = NULL;
int i;
char xlogstart[64];
char xlogend[64];
int minServerMajor,
maxServerMajor;
int serverVersion,
serverMajor;
//數(shù)據(jù)庫(kù)連接
Assert(conn != NULL);
/*
* Check server version. BASE_BACKUP command was introduced in 9.1, so we
* can't work with servers older than 9.1.
* 檢查服務(wù)器版本.BASE_BACKUP在9.1+才出現(xiàn),數(shù)據(jù)庫(kù)版本不能低于9.1.
*/
minServerMajor = 901;
maxServerMajor = PG_VERSION_NUM / 100;
serverVersion = PQserverVersion(conn);
serverMajor = serverVersion / 100;
if (serverMajor < minServerMajor || serverMajor > maxServerMajor)
{
const char *serverver = PQparameterStatus(conn, "server_version");
fprintf(stderr, _("%s: incompatible server version %s\n"),
progname, serverver ? serverver : "'unknown'");
exit(1);
}
/*
* If WAL streaming was requested, also check that the server is new
* enough for that.
* 要求WAL streaming,檢查數(shù)據(jù)庫(kù)是否支持
*/
if (includewal == STREAM_WAL && !CheckServerVersionForStreaming(conn))
{
/*
* Error message already written in CheckServerVersionForStreaming(),
* but add a hint about using -X none.
* 錯(cuò)誤信息已在CheckServerVersionForStreaming()中體現(xiàn),這里添加-X提示.
*/
fprintf(stderr, _("HINT: use -X none or -X fetch to disable log streaming\n"));
exit(1);
}
/*
* Build contents of configuration file if requested
* 如需要?jiǎng)?chuàng)建recovery.conf文件
*/
if (writerecoveryconf)
GenerateRecoveryConf(conn);
/*
* Run IDENTIFY_SYSTEM so we can get the timeline
* 執(zhí)行RunIdentifySystem,獲取時(shí)間線(xiàn)
*/
if (!RunIdentifySystem(conn, &sysidentifier, &latesttli, NULL, NULL))
exit(1);
/*
* Start the actual backup
* 開(kāi)始實(shí)際的backup
*/
PQescapeStringConn(conn, escaped_label, label, sizeof(escaped_label), &i);
if (maxrate > 0)
maxrate_clause = psprintf("MAX_RATE %u", maxrate);
if (verbose)
//提示信息
fprintf(stderr,
_("%s: initiating base backup, waiting for checkpoint to complete\n"),
progname);
if (showprogress && !verbose)
{
//進(jìn)度信息
fprintf(stderr, "waiting for checkpoint");
if (isatty(fileno(stderr)))
fprintf(stderr, "\r");
else
fprintf(stderr, "\n");
}
//base backup命令
basebkp =
psprintf("BASE_BACKUP LABEL '%s' %s %s %s %s %s %s %s",
escaped_label,
showprogress ? "PROGRESS" : "",
includewal == FETCH_WAL ? "WAL" : "",
fastcheckpoint ? "FAST" : "",
includewal == NO_WAL ? "" : "NOWAIT",
maxrate_clause ? maxrate_clause : "",
format == 't' ? "TABLESPACE_MAP" : "",
verify_checksums ? "" : "NOVERIFY_CHECKSUMS");
//調(diào)用API
if (PQsendQuery(conn, basebkp) == 0)
{
fprintf(stderr, _("%s: could not send replication command \"%s\": %s"),
progname, "BASE_BACKUP", PQerrorMessage(conn));
exit(1);
}
/*
* Get the starting WAL location
* 獲取WAL起始位置
*/
//獲取PQ執(zhí)行結(jié)果
res = PQgetResult(conn);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
fprintf(stderr, _("%s: could not initiate base backup: %s"),
progname, PQerrorMessage(conn));
exit(1);
}
//判斷ntuples
if (PQntuples(res) != 1)
{
fprintf(stderr,
_("%s: server returned unexpected response to BASE_BACKUP command; got %d rows and %d fields, expected %d rows and %d fields\n"),
progname, PQntuples(res), PQnfields(res), 1, 2);
exit(1);
}
//獲取WAL start位置
strlcpy(xlogstart, PQgetvalue(res, 0, 0), sizeof(xlogstart));
if (verbose)
fprintf(stderr, _("%s: checkpoint completed\n"), progname);
/*
* 9.3 and later sends the TLI of the starting point. With older servers,
* assume it's the same as the latest timeline reported by
* IDENTIFY_SYSTEM.
* 9.3+在起始點(diǎn)就傳送了TLI.
*/
if (PQnfields(res) >= 2)
starttli = atoi(PQgetvalue(res, 0, 1));
else
starttli = latesttli;
PQclear(res);
MemSet(xlogend, 0, sizeof(xlogend));
if (verbose && includewal != NO_WAL)
fprintf(stderr, _("%s: write-ahead log start point: %s on timeline %u\n"),
progname, xlogstart, starttli);
/*
* Get the header
* 獲取頭部信息
*/
res = PQgetResult(conn);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
fprintf(stderr, _("%s: could not get backup header: %s"),
progname, PQerrorMessage(conn));
exit(1);
}
if (PQntuples(res) < 1)
{
fprintf(stderr, _("%s: no data returned from server\n"), progname);
exit(1);
}
/*
* Sum up the total size, for progress reporting
* 統(tǒng)計(jì)總大小,用于進(jìn)度報(bào)告
*/
totalsize = totaldone = 0;
tablespacecount = PQntuples(res);
for (i = 0; i < PQntuples(res); i++)
{
totalsize += atol(PQgetvalue(res, i, 2));
/*
* Verify tablespace directories are empty. Don't bother with the
* first once since it can be relocated, and it will be checked before
* we do anything anyway.
* 驗(yàn)證表空間目錄是否為空.
* 首次驗(yàn)證不需要報(bào)警,因?yàn)榭梢灾匦露ㄎ徊⑶以谧髌渌虑榍皶?huì)檢查.
*/
if (format == 'p' && !PQgetisnull(res, i, 1))
{
char *path = unconstify(char *, get_tablespace_mapping(PQgetvalue(res, i, 1)));
verify_dir_is_empty_or_create(path, &made_tablespace_dirs, &found_tablespace_dirs);
}
}
/*
* When writing to stdout, require a single tablespace
* 在寫(xiě)入stdout時(shí),要求一個(gè)獨(dú)立的表空間.
*/
if (format == 't' && strcmp(basedir, "-") == 0 && PQntuples(res) > 1)
{
fprintf(stderr,
_("%s: can only write single tablespace to stdout, database has %d\n"),
progname, PQntuples(res));
exit(1);
}
/*
* If we're streaming WAL, start the streaming session before we start
* receiving the actual data chunks.
* 如果正在streaming WAL,開(kāi)始接收實(shí)際的數(shù)據(jù)chunks前,開(kāi)始streaming session.
*/
if (includewal == STREAM_WAL)
{
if (verbose)
fprintf(stderr, _("%s: starting background WAL receiver\n"),
progname);
StartLogStreamer(xlogstart, starttli, sysidentifier);
}
/*
* Start receiving chunks
* 開(kāi)始接收chunks
*/
for (i = 0; i < PQntuples(res); i++)//所有的表空間
{
if (format == 't')
//tar包
ReceiveTarFile(conn, res, i);
else
//普通文件
ReceiveAndUnpackTarFile(conn, res, i);
} /* Loop over all tablespaces */
if (showprogress)
{
progress_report(PQntuples(res), NULL, true);
if (isatty(fileno(stderr)))
fprintf(stderr, "\n"); /* Need to move to next line */
}
PQclear(res);
/*
* Get the stop position
*/
res = PQgetResult(conn);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
fprintf(stderr,
_("%s: could not get write-ahead log end position from server: %s"),
progname, PQerrorMessage(conn));
exit(1);
}
if (PQntuples(res) != 1)
{
fprintf(stderr,
_("%s: no write-ahead log end position returned from server\n"),
progname);
exit(1);
}
strlcpy(xlogend, PQgetvalue(res, 0, 0), sizeof(xlogend));
if (verbose && includewal != NO_WAL)
fprintf(stderr, _("%s: write-ahead log end point: %s\n"), progname, xlogend);
PQclear(res);
//
res = PQgetResult(conn);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
const char *sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
if (sqlstate &&
strcmp(sqlstate, ERRCODE_DATA_CORRUPTED) == 0)
{
fprintf(stderr, _("%s: checksum error occurred\n"),
progname);
checksum_failure = true;
}
else
{
fprintf(stderr, _("%s: final receive failed: %s"),
progname, PQerrorMessage(conn));
}
exit(1);
}
if (bgchild > 0)
{
#ifndef WIN32
int status;
pid_t r;
#else
DWORD status;
/*
* get a pointer sized version of bgchild to avoid warnings about
* casting to a different size on WIN64.
*/
intptr_t bgchild_handle = bgchild;
uint32 hi,
lo;
#endif
if (verbose)
fprintf(stderr,
_("%s: waiting for background process to finish streaming ...\n"), progname);
#ifndef WIN32//WIN32
if (write(bgpipe[1], xlogend, strlen(xlogend)) != strlen(xlogend))
{
fprintf(stderr,
_("%s: could not send command to background pipe: %s\n"),
progname, strerror(errno));
exit(1);
}
/* Just wait for the background process to exit */
r = waitpid(bgchild, &status, 0);
if (r == (pid_t) -1)
{
fprintf(stderr, _("%s: could not wait for child process: %s\n"),
progname, strerror(errno));
exit(1);
}
if (r != bgchild)
{
fprintf(stderr, _("%s: child %d died, expected %d\n"),
progname, (int) r, (int) bgchild);
exit(1);
}
if (status != 0)
{
fprintf(stderr, "%s: %s\n",
progname, wait_result_to_str(status));
exit(1);
}
/* Exited normally, we're happy! */
#else /* WIN32 */
/*
* On Windows, since we are in the same process, we can just store the
* value directly in the variable, and then set the flag that says
* it's there.
* 在Windows平臺(tái),因?yàn)樵谕粋€(gè)進(jìn)程中,只需要直接存儲(chǔ)值到遍歷中,然后設(shè)置標(biāo)記即可.
*/
if (sscanf(xlogend, "%X/%X", &hi, &lo) != 2)
{
fprintf(stderr,
_("%s: could not parse write-ahead log location \"%s\"\n"),
progname, xlogend);
exit(1);
}
xlogendptr = ((uint64) hi) << 32 | lo;
InterlockedIncrement(&has_xlogendptr);
/* First wait for the thread to exit */
if (WaitForSingleObjectEx((HANDLE) bgchild_handle, INFINITE, FALSE) !=
WAIT_OBJECT_0)
{
_dosmaperr(GetLastError());
fprintf(stderr, _("%s: could not wait for child thread: %s\n"),
progname, strerror(errno));
exit(1);
}
if (GetExitCodeThread((HANDLE) bgchild_handle, &status) == 0)
{
_dosmaperr(GetLastError());
fprintf(stderr, _("%s: could not get child thread exit status: %s\n"),
progname, strerror(errno));
exit(1);
}
if (status != 0)
{
fprintf(stderr, _("%s: child thread exited with error %u\n"),
progname, (unsigned int) status);
exit(1);
}
/* Exited normally, we're happy */
#endif
}
/* Free the configuration file contents */
//釋放配置文件內(nèi)存
destroyPQExpBuffer(recoveryconfcontents);
/*
* End of copy data. Final result is already checked inside the loop.
* 拷貝數(shù)據(jù)完成.最終結(jié)果已在循環(huán)中檢查.
*/
PQclear(res);
PQfinish(conn);
conn = NULL;
/*
* Make data persistent on disk once backup is completed. For tar format
* once syncing the parent directory is fine, each tar file created per
* tablespace has been already synced. In plain format, all the data of
* the base directory is synced, taking into account all the tablespaces.
* Errors are not considered fatal.
* 在備份結(jié)束后,持久化數(shù)據(jù)在磁盤(pán)上.
* 對(duì)于tar格式只需要同步父目錄即可,每一個(gè)表空間創(chuàng)建一個(gè)tar文件,這些文件已同步.
* 對(duì)于普通格式,基礎(chǔ)目錄中的所有數(shù)據(jù)已同步,已兼顧了所有的表空間.
* 錯(cuò)誤不會(huì)認(rèn)為是致命的異常.
*/
if (do_sync)
{
if (verbose)
fprintf(stderr,
_("%s: syncing data to disk ...\n"), progname);
if (format == 't')
{
if (strcmp(basedir, "-") != 0)
(void) fsync_fname(basedir, true, progname);
}
else
{
(void) fsync_pgdata(basedir, progname, serverVersion);
}
}
if (verbose)
fprintf(stderr, _("%s: base backup completed\n"), progname);
}
/*
* PQgetvalue:
* return the value of field 'field_num' of row 'tup_num'
* 返回tuples數(shù)組第field_num字段的第tup_num行.
*/
char *
PQgetvalue(const PGresult *res, int tup_num, int field_num)
{
if (!check_tuple_field_number(res, tup_num, field_num))
return NULL;
return res->tuples[tup_num][field_num].value;
}
備份命令
pg_basebackup -h localhost -U xdb -p 5432 -D /data/backup -P -Xs -R
啟動(dòng)gdb跟蹤
[xdb@localhost ~]$ gdb pg_basebackup
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-110.el7
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
連接pg_conn結(jié)構(gòu)體
(gdb) n
1749 Assert(conn != NULL);
(gdb) p *conn
$1 = {pghost = 0x6282d0 "localhost", pghostaddr = 0x0, pgport = 0x6282f0 "5432", pgtty = 0x628310 "",
connect_timeout = 0x0, client_encoding_initial = 0x0, pgoptions = 0x628330 "", appname = 0x0,
fbappname = 0x628350 "pg_basebackup", dbName = 0x6282b0 "replication", replication = 0x6283d0 "true",
pguser = 0x628290 "xdb", pgpass = 0x0, pgpassfile = 0x628d30 "/home/xdb/.pgpass", keepalives = 0x0,
keepalives_idle = 0x0, keepalives_interval = 0x0, keepalives_count = 0x0, sslmode = 0x628370 "prefer",
sslcompression = 0x628390 "0", sslkey = 0x0, sslcert = 0x0, sslrootcert = 0x0, sslcrl = 0x0, requirepeer = 0x0,
krbsrvname = 0x6283b0 "postgres", target_session_attrs = 0x6283f0 "any", Pfdebug = 0x0, noticeHooks = {
noticeRec = 0x7ffff7b9eab4 , noticeRecArg = 0x0,
noticeProc = 0x7ffff7b9eb09 , noticeProcArg = 0x0}, events = 0x0, nEvents = 0,
eventArraySize = 0, status = CONNECTION_OK, asyncStatus = PGASYNC_IDLE, xactStatus = PQTRANS_IDLE,
queryclass = PGQUERY_SIMPLE, last_query = 0x61f1c0 "SHOW wal_segment_size", last_sqlstate = "\000\000\000\000\000",
options_valid = true, nonblocking = false, singleRowMode = false, copy_is_binary = 0 '\000', copy_already_done = 0,
notifyHead = 0x0, notifyTail = 0x0, nconnhost = 1, whichhost = 0, connhost = 0x627a50, sock = 7, laddr = {addr = {
ss_family = 10, __ss_padding = "\307\326", '\000' , "\001", '\000' ,
__ss_align = 0}, salen = 28}, raddr = {addr = {ss_family = 10,
__ss_padding = "\025\070", '\000' , "\001", '\000' , __ss_align = 0},
salen = 28}, pversion = 196608, sversion = 110002, auth_req_received = true, password_needed = false,
sigpipe_so = false, sigpipe_flag = true, try_next_addr = false, try_next_host = false, addr_cur = 0x0,
setenv_state = SETENV_STATE_IDLE, next_eo = 0x0, send_appname = true, be_pid = 1435, be_key = -828773845,
pstatus = 0x629570, client_encoding = 0, std_strings = true, verbosity = PQERRORS_DEFAULT,
show_context = PQSHOW_CONTEXT_ERRORS, lobjfuncs = 0x0, inBuffer = 0x61f600 "T", inBufSize = 16384, inStart = 75,
inCursor = 75, inEnd = 75, outBuffer = 0x623610 "Q", outBufSize = 16384, outCount = 0, outMsgStart = 1, outMsgEnd = 27,
rowBuf = 0x627620, rowBufLen = 32, result = 0x0, next_result = 0x0, sasl_state = 0x0, ssl_in_use = false,
allow_ssl_try = false, wait_ssl_try = false, ssl = 0x0, peer = 0x0, engine = 0x0, gctx = 0x0, gtarg_nam = 0x0,
errorMessage = {data = 0x627830 "", len = 0, maxlen = 256}, workBuffer = {data = 0x627940 "SELECT", len = 6,
maxlen = 256}, addrlist = 0x0, addrlist_family = 0}
(gdb)
判斷版本,是否支持BaseBackup
(gdb) n
1755 minServerMajor = 901;
(gdb)
1756 maxServerMajor = PG_VERSION_NUM / 100;
(gdb) p PG_VERSION_NUM
$2 = 110002
(gdb) n
1757 serverVersion = PQserverVersion(conn);
(gdb)
1758 serverMajor = serverVersion / 100;
(gdb)
1759 if (serverMajor < minServerMajor || serverMajor > maxServerMajor)
(gdb) p serverVersion
$3 = 110002
(gdb) n
判斷服務(wù)器是否支持WAL streaming
(gdb) n
1772 if (includewal == STREAM_WAL && !CheckServerVersionForStreaming(conn))
(gdb)
如需要,生成recovery.conf文件
1785 if (writerecoveryconf)
(gdb) p includewal
$4 = STREAM_WAL
(gdb) p writerecoveryconf
$5 = true
(gdb) n
1786 GenerateRecoveryConf(conn);
(gdb)
獲取系統(tǒng)標(biāo)識(shí)符
1791 if (!RunIdentifySystem(conn, &sysidentifier, &latesttli, NULL, NULL))
(gdb)
1797 PQescapeStringConn(conn, escaped_label, label, sizeof(escaped_label), &i);
(gdb) p sysidentifier
$6 = 0x6292d0 "6662151435832250464"
(gdb) p *sysidentifier
$7 = 54 '6'
(gdb) p latesttli
$8 = 1
(gdb)
開(kāi)始實(shí)際的備份工作
(gdb) p escaped_label
$9 = "pg_basebackup base backup\000\000\000\001", '\000' , "\"`-\360\377\177\000\000\000\000\000\000\377\177\000\000` u\367\377\177\000\000\000\001\000\000\000\000\000\000\001\000\000\000\002\000\000\000]VA\000\000\000\000\000@\335\377\377\377\177\000\000b\343\377\377\377\177", '\000' , "\343\377\377\377\177\000\000B\335\377\377\377\177\000\000\370?\367\377\177\000\000\220\325\227\367\377\177\000\000\000\341\377\377\377\177\000\000\000\000\000\000\000\000\000\000\371D"...
(gdb) p label
$10 = 0x412610 "pg_basebackup base backup"
(gdb) p i
$11 = 0
(gdb)
構(gòu)造backup命令
(gdb) n
1802 if (verbose)
(gdb)
1807 if (showprogress && !verbose)
(gdb)
1809 fprintf(stderr, "waiting for checkpoint");
(gdb)
waiting for checkpoint1810 if (isatty(fileno(stderr)))
(gdb)
1811 fprintf(stderr, "\r");
(gdb)
1817 psprintf("BASE_BACKUP LABEL '%s' %s %s %s %s %s %s %s",
(gdb)
1824 format == 't' ? "TABLESPACE_MAP" : "",
(gdb)
1817 psprintf("BASE_BACKUP LABEL '%s' %s %s %s %s %s %s %s",
(gdb)
1822 includewal == NO_WAL ? "" : "NOWAIT",
(gdb)
1817 psprintf("BASE_BACKUP LABEL '%s' %s %s %s %s %s %s %s",
(gdb)
1820 includewal == FETCH_WAL ? "WAL" : "",
(gdb)
1817 psprintf("BASE_BACKUP LABEL '%s' %s %s %s %s %s %s %s",
(gdb)
1816 basebkp =
(gdb)
1827 if (PQsendQuery(conn, basebkp) == 0)
(gdb)
(gdb) p basebkp
$12 = 0x6291f0 "BASE_BACKUP LABEL 'pg_basebackup base backup' PROGRESS NOWAIT "
(gdb)
發(fā)送命令到服務(wù)器端,獲取執(zhí)行結(jié)果
(gdb) n
1837 res = PQgetResult(conn);
(gdb)
1838 if (PQresultStatus(res) != PGRES_TUPLES_OK)
(gdb)
返回結(jié)果
(gdb) p *res
$13 = {ntups = 1, numAttributes = 2, attDescs = 0x629688, tuples = 0x629e90, tupArrSize = 128, numParameters = 0,
paramDescs = 0x0, resultStatus = PGRES_TUPLES_OK,
cmdStatus = "SELECT\000\000\000\000\000\000\000\000\000\000\027\000\000\000\004\000\000\000\377\377\377\377:\226b", '\000' , "\031\000\000\000\377\377\377\377\377\377\377\377B\226b", binary = 0, noticeHooks = {
noticeRec = 0x7ffff7b9eab4 , noticeRecArg = 0x0,
noticeProc = 0x7ffff7b9eb09 , noticeProcArg = 0x0}, events = 0x0, nEvents = 0,
client_encoding = 0, errMsg = 0x0, errFields = 0x0, errQuery = 0x0, null_field = "", curBlock = 0x629680,
curOffset = 133, spaceLeft = 1915}
(gdb)
(gdb) p *res->attDescs
$14 = {name = 0x6296c8 "recptr", tableid = 0, columnid = 0, format = 0, typid = 25, typlen = -1, atttypmod = 0}
(gdb) p *res->tuples
$15 = (PGresAttValue *) 0x6296d8
(gdb) p **res->tuples
$16 = {len = 10, value = 0x6296f8 "1/57000028"}
(gdb) p *res->tuples[2]
Cannot access memory at address 0x0
(gdb) p *res->tuples[0]
$17 = {len = 10, value = 0x6296f8 "1/57000028"}
(gdb) p *res->tuples[1]
Cannot access memory at address 0x15171
(gdb)
判斷ntuples,獲取WAL start位置
(gdb) n
1844 if (PQntuples(res) != 1)
(gdb)
1852 strlcpy(xlogstart, PQgetvalue(res, 0, 0), sizeof(xlogstart));
(gdb) p PQgetvalue(res, 0, 0)
$18 = 0x6296f8 "1/57000028"
(gdb) p xlogstart
$19 = " `-\360\377\177\000\000\353\340\377\377\377\177\000\000\360\340a", '\000' , "\360\337\377\377\377\177", '\000'
(gdb) n
1854 if (verbose)
(gdb) p xlogstart
$20 = "1/57000028\000\377\377\177\000\000\360\340a", '\000' , "\360\337\377\377\377\177", '\000'
(gdb)
獲取時(shí)間線(xiàn)timeline
(gdb) n
1862 if (PQnfields(res) >= 2)
(gdb) p PQnfields(res)
$21 = 2
(gdb) n
1863 starttli = atoi(PQgetvalue(res, 0, 1));
(gdb)
1866 PQclear(res);
(gdb) p atoi(PQgetvalue(res, 0, 1))
$22 = 1
(gdb) p res->tuples[1]
$23 = (PGresAttValue *) 0x15171
(gdb) p res->tuples[0]
$24 = (PGresAttValue *) 0x6296d8
(gdb)
(gdb) n
1867 MemSet(xlogend, 0, sizeof(xlogend));
(gdb)
1869 if (verbose && includewal != NO_WAL)
(gdb) p xlogend
$25 = '\000'
Get the header
(gdb) n
1876 res = PQgetResult(conn);
(gdb) n
1877 if (PQresultStatus(res) != PGRES_TUPLES_OK)
(gdb) p *res
$26 = {ntups = 1, numAttributes = 3, attDescs = 0x629688, tuples = 0x629e90, tupArrSize = 128, numParameters = 0,
paramDescs = 0x0, resultStatus = PGRES_TUPLES_OK,
cmdStatus = "SELECT\000\000\000\000\000\000\000\000\000\000\027\000\000\000\004\000\000\000\377\377\377\377:\226b", '\000' , "\031\000\000\000\377\377\377\377\377\377\377\377B\226b", binary = 0, noticeHooks = {
noticeRec = 0x7ffff7b9eab4 , noticeRecArg = 0x0,
noticeProc = 0x7ffff7b9eb09 , noticeProcArg = 0x0}, events = 0x0, nEvents = 0,
client_encoding = 0, errMsg = 0x0, errFields = 0x0, errQuery = 0x0, null_field = "", curBlock = 0x629680,
curOffset = 183, spaceLeft = 1865}
統(tǒng)計(jì)總大小,用于進(jìn)度報(bào)告
(gdb)
1892 totalsize = totaldone = 0;
(gdb) n
1893 tablespacecount = PQntuples(res);
(gdb)
1894 for (i = 0; i < PQntuples(res); i++)
(gdb) p tablespacecount
$29 = 1
(gdb) n
1896 totalsize += atol(PQgetvalue(res, i, 2));
(gdb) p PQgetvalue(res, i, 2)
$30 = 0x629730 "445480"
(gdb) p atol(PQgetvalue(res, i, 2))
$31 = 445480
(gdb) n
1903 if (format == 'p' && !PQgetisnull(res, i, 1))
(gdb)
1894 for (i = 0; i < PQntuples(res); i++)
(gdb) p res->tuples[0][0]
$33 = {len = -1, value = 0x629658 ""}
(gdb) p res->tuples[0][1]
$34 = {len = -1, value = 0x629658 ""}
(gdb) p res->tuples[0][2]
$35 = {len = 6, value = 0x629730 "445480"}
(gdb)
開(kāi)始接收實(shí)際的數(shù)據(jù)chunks前,開(kāi)始streaming session.
(gdb) n
1914 if (format == 't' && strcmp(basedir, "-") == 0 && PQntuples(res) > 1)
(gdb)
1926 if (includewal == STREAM_WAL)
(gdb)
1928 if (verbose)
(gdb)
1931 StartLogStreamer(xlogstart, starttli, sysidentifier);
(gdb) n
Detaching after fork from child process 1511.
1937 for (i = 0; i < PQntuples(res); i++)
(gdb)
查看操作系統(tǒng)中的日志目錄
[xdb@localhost backup]$ ll
total 0
drwx------. 3 xdb xdb 60 Mar 15 15:46 pg_wal
[xdb@localhost backup]$ ll ./pg_wal/
total 16384
-rw-------. 1 xdb xdb 16777216 Mar 15 15:46 000000010000000100000057
drwx------. 2 xdb xdb 6 Mar 15 15:46 archive_status
[xdb@localhost backup]$
Start receiving chunks,開(kāi)始接收chunks
(gdb) n
Detaching after fork from child process 1511.
1937 for (i = 0; i < PQntuples(res); i++)
(gdb) n
1939 if (format == 't')
(gdb)
1942 ReceiveAndUnpackTarFile(conn, res, i);
(gdb)
193789/445489 kB
(gdb) for (i = 0; i < PQntuples(res); i++)
查看操作系統(tǒng)中的備份目錄
[xdb@localhost backup]$ ll
total 56
-rw-------. 1 xdb xdb 226 Mar 15 15:47 backup_label
drwx------. 6 xdb xdb 58 Mar 15 15:48 base
drwx------. 2 xdb xdb 4096 Mar 15 15:48 global
drwx------. 2 xdb xdb 6 Mar 15 15:47 pg_commit_ts
drwx------. 2 xdb xdb 6 Mar 15 15:47 pg_dynshmem
-rw-------. 1 xdb xdb 4513 Mar 15 15:48 pg_hba.conf
-rw-------. 1 xdb xdb 1636 Mar 15 15:48 pg_ident.conf
drwx------. 4 xdb xdb 68 Mar 15 15:48 pg_logical
drwx------. 4 xdb xdb 36 Mar 15 15:47 pg_multixact
drwx------. 2 xdb xdb 6 Mar 15 15:47 pg_notify
drwx------. 2 xdb xdb 6 Mar 15 15:48 pg_replslot
drwx------. 2 xdb xdb 6 Mar 15 15:47 pg_serial
drwx------. 2 xdb xdb 6 Mar 15 15:47 pg_snapshots
drwx------. 2 xdb xdb 6 Mar 15 15:48 pg_stat
drwx------. 2 xdb xdb 6 Mar 15 15:48 pg_stat_tmp
drwx------. 2 xdb xdb 6 Mar 15 15:47 pg_subtrans
drwx------. 2 xdb xdb 6 Mar 15 15:48 pg_tblspc
drwx------. 2 xdb xdb 6 Mar 15 15:47 pg_twophase
-rw-------. 1 xdb xdb 3 Mar 15 15:48 PG_VERSION
drwx------. 3 xdb xdb 92 Mar 15 15:48 pg_wal
drwx------. 2 xdb xdb 18 Mar 15 15:48 pg_xact
-rw-------. 1 xdb xdb 88 Mar 15 15:48 postgresql.auto.conf
-rw-------. 1 xdb xdb 23812 Mar 15 15:48 postgresql.conf
-rw-------. 1 xdb xdb 183 Mar 15 15:48 recovery.conf
[xdb@localhost backup]$
顯示進(jìn)度
(gdb) n
1945 if (showprogress)
(gdb)
1947 progress_report(PQntuples(res), NULL, true);
(gdb)
194889/445489 kB (100%),if (isatty(fileno(stderr)))
(gdb)
(gdb) n
1949 fprintf(stderr, "\n"); /* Need to move to next line */
(gdb)
1952 PQclear(res);
(gdb)
Get the stop position
(gdb)
1957 res = PQgetResult(conn);
(gdb) n
1958 if (PQresultStatus(res) != PGRES_TUPLES_OK)
(gdb) p *res
$36 = {ntups = 1, numAttributes = 2, attDescs = 0x6295a8, tuples = 0x629db0, tupArrSize = 128, numParameters = 0,
paramDescs = 0x0, resultStatus = PGRES_TUPLES_OK,
cmdStatus = "SELECT", '\000' , "\300!", , binary = 0, noticeHooks = {
noticeRec = 0x7ffff7b9eab4 , noticeRecArg = 0x0,
noticeProc = 0x7ffff7b9eb09 , noticeProcArg = 0x0}, events = 0x0, nEvents = 0,
client_encoding = 0, errMsg = 0x0, errFields = 0x0, errQuery = 0x0, null_field = "", curBlock = 0x6295a0,
curOffset = 133, spaceLeft = 1915}
(gdb)
(gdb) n
1965 if (PQntuples(res) != 1)
(gdb)
1972 strlcpy(xlogend, PQgetvalue(res, 0, 0), sizeof(xlogend));
(gdb) p xlogend
$37 = '\000'
(gdb) p *xlogend
$38 = 0 '\000'
(gdb) n
1973 if (verbose && includewal != NO_WAL)
(gdb)
1975 PQclear(res);
(gdb)
COMMAND is OK
(gdb)
1977 res = PQgetResult(conn);
(gdb)
1978 if (PQresultStatus(res) != PGRES_COMMAND_OK)
(gdb) p *res
$39 = {ntups = 0, numAttributes = 0, attDescs = 0x0, tuples = 0x0, tupArrSize = 0, numParameters = 0, paramDescs = 0x0,
resultStatus = PGRES_COMMAND_OK, cmdStatus = "SELECT", '\000' , "\300!", ,
binary = 0, noticeHooks = {noticeRec = 0x7ffff7b9eab4 , noticeRecArg = 0x0,
noticeProc = 0x7ffff7b9eb09 , noticeProcArg = 0x0}, events = 0x0, nEvents = 0,
client_encoding = 0, errMsg = 0x0, errFields = 0x0, errQuery = 0x0, null_field = "", curBlock = 0x0, curOffset = 0,
spaceLeft = 0}
(gdb)
善后工作,如在備份結(jié)束后,持久化數(shù)據(jù)在磁盤(pán)上等
(gdb) n
1997 if (bgchild > 0)
(gdb)
2014 if (verbose)
(gdb)
2019 if (write(bgpipe[1], xlogend, strlen(xlogend)) != strlen(xlogend))
(gdb)
2028 r = waitpid(bgchild, &status, 0);
(gdb) p bgchild
$40 = 1511
(gdb) n
2029 if (r == -1)
(gdb)
2035 if (r != bgchild)
(gdb) p r
$41 = 1511
(gdb) n
2041 if (!WIFEXITED(status))
(gdb)
2047 if (WEXITSTATUS(status) != 0)
(gdb)
2098 destroyPQExpBuffer(recoveryconfcontents);
(gdb)
2103 PQclear(res);
(gdb)
2104 PQfinish(conn);
(gdb)
2113 if (do_sync)
(gdb)
2115 if (format == 't')
(gdb)
2122 (void) fsync_pgdata(basedir, progname, serverVersion);
(gdb)
2126 if (verbose)
(gdb)
2128 }
(gdb)
main (argc=12, argv=0x7fffffffe4b8) at pg_basebackup.c:2534
2534 success = true;
(gdb)
再次啟動(dòng)跟蹤,監(jiān)控后臺(tái)數(shù)據(jù)庫(kù)的活動(dòng).
進(jìn)入BaseBackup函數(shù)
Breakpoint 1, BaseBackup () at pg_basebackup.c:1740
1740 char *maxrate_clause = NULL;
(gdb)
數(shù)據(jù)庫(kù)活動(dòng)
15:56:25 (xdb@[local]:5432)testdb=# select * from pg_stat_activity
[local] xdb@testdb-# where backend_type not in ('walwriter', 'checkpointer', 'background writer', 'logical replication launcher', 'autovacuum launcher') and query not like '%pg_stat_activity%';
-[ RECORD 1 ]----+------------------------------
datid |
datname |
pid | 1566
usesysid | 10
usename | xdb
application_name | pg_basebackup
client_addr | ::1
client_hostname |
client_port | 51162
backend_start | 2019-03-15 15:56:13.82013+08
xact_start |
query_start |
state_change | 2019-03-15 15:56:13.821507+08
wait_event_type | Client
wait_event | ClientRead
state | idle
backend_xid |
backend_xmin |
query |
backend_type | walsender
開(kāi)啟WAL streaming
1931 StartLogStreamer(xlogstart, starttli, sysidentifier);
(gdb)
Detaching after fork from child process 1602.
1937 for (i = 0; i < PQntuples(res); i++)
(gdb)
數(shù)據(jù)庫(kù)活動(dòng)
16:01:25 (xdb@[local]:5432)testdb=# select * from pg_stat_activity
where backend_type not in ('walwriter', 'checkpointer', 'background writer', 'logical replication launcher', 'autovacuum launcher') and query not like '%pg_stat_activity%';
-[ RECORD 1 ]----+------------------------------
datid |
datname |
pid | 1566
usesysid | 10
usename | xdb
application_name | pg_basebackup
client_addr | ::1
client_hostname |
client_port | 51162
backend_start | 2019-03-15 15:56:13.82013+08
xact_start |
query_start |
state_change | 2019-03-15 16:00:47.345326+08
wait_event_type | Client
wait_event | ClientWrite
state | active
backend_xid |
backend_xmin |
query |
backend_type | walsender
-[ RECORD 2 ]----+------------------------------
datid |
datname |
pid | 1601
usesysid | 10
usename | xdb
application_name | pg_basebackup
client_addr | ::1
client_hostname |
client_port | 51164
backend_start | 2019-03-15 16:01:47.150434+08
xact_start |
query_start |
state_change | 2019-03-15 16:01:47.159234+08
wait_event_type | Activity
wait_event | WalSenderMain
state | active
backend_xid |
backend_xmin |
query |
backend_type | walsender
16:01:56 (xdb@[local]:5432)testdb=#
16:01:56 (xdb@[local]:5432)testdb=
拷貝數(shù)據(jù)
(gdb)
1942 ReceiveAndUnpackTarFile(conn, res, i);
(gdb)
193789/445489 kBfor (i = 0; i < PQntuples(res); i++)
(gdb)
1945 if (showprogress)
(gdb)
數(shù)據(jù)庫(kù)活動(dòng)
...
-[ RECORD 3 ]----+------------------------------
datid |
datname |
pid | 1352
usesysid |
usename |
application_name |
client_addr |
client_hostname |
client_port |
backend_start | 2019-03-15 15:03:01.923092+08
xact_start |
query_start |
state_change |
wait_event_type | Activity
wait_event | WalWriterMain
state |
backend_xid |
backend_xmin |
query |
backend_type | walwriter
執(zhí)行善后工作
2113 if (do_sync)
(gdb)
2115 if (format == 't')
(gdb)
2122 (void) fsync_pgdata(basedir, progname, serverVersion);
(gdb)
2126 if (verbose)
(gdb)
2128 }
(gdb)
數(shù)據(jù)庫(kù)活動(dòng)
16:05:01 (xdb@[local]:5432)testdb=# select * from pg_stat_activity
where backend_type not in ('checkpointer', 'background writer', 'logical replication launcher', 'autovacuum launcher') and query not like '%pg_stat_activity%';
-[ RECORD 1 ]----+------------------------------
datid |
datname |
pid | 1352
usesysid |
usename |
application_name |
client_addr |
client_hostname |
client_port |
backend_start | 2019-03-15 15:03:01.923092+08
xact_start |
query_start |
state_change |
wait_event_type | Activity
wait_event | WalWriterMain
state |
backend_xid |
backend_xmin |
query |
backend_type | walwriter
DONE!
PG Source Code
